Residual coding for color components

Abstract

Methods, devices, and non-transitory storage mediums are provided for video coding. In one method, a decoder may determine whether joint residual coding of multiple color components is applied to a video block and obtain one or more syntax elements indicating a weight associated with a first color component in response to determining that the joint residual coding of multiple color components is applied to the video block. Furthermore, the decoder may decode a second residual block of a second color component and derive a first residual block of the first color component based on the one or more syntax elements and the second residual block.

Description

Attorney Ref.: 186015.20231 RESIDUAL CODING FOR COLOR COMPONENTS CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is based upon and claims priority to Provisional Application No.63 / 696,555 filed on September 19, 2024, the entire content thereof is incorporated herein by reference in its entirety for all purposes. TECHNICAL FIELD

[0002] This application is related to video coding and compression. More specifically, thisapplication relates to joint coding of residuals from different color components. BACKGROUND

[0003] Digital video is supported by a variety of electronic devices. The electronic devicestransmit and receive or otherwise communicate digital video data across a communication network, and / or store the digital video data on a storage device. Due to a limited bandwidth capacity of the communication network and limited memory resources of the storage device, video coding may be used to compress the video data according to one or more video coding standards before it is communicated or stored, to generate encoded video data that uses a lower bit rate, while avoiding or minimizing degradations to video quality. SUMMARY

[0004] Embodiments of the present disclosure provide details of the proposed improvementson joint coding of residuals form different color components.

[0005] According to a first aspect of the present application, a video decoding method isprovided. The method may include that: a decoder may determine whether a joint residual coding from multiple color components is applied to a video block. The decoder may obtain one or more syntax elements indicating a weight value associated with a first color component in response to determining that the joint residual coding of multiple color components is applied to the video block. The decoder may decode a second residual block of a second color component and derive a first residual block of the first color component based on the one or more syntax elements and the second residual block.

[0006] According to a second aspect of the present application, a video encoding method isprovided. The method may include that: an encoder may determine one or more syntax elements indicating a weight value associated with a first color component, where joint residual coding from multiple color components is applied to a video block, and the weight value is selected from aAttorney Ref.: 186015.20231 plurality of predefined weight values. The encoder may signal a joint residual block and the one or more syntax elements indicating the weight value associated with the first color component, where the joint residual block corresponds to a second color components, and the multiple color components comprise the first and second color components. Furthermore, the encoder may transmit a bitstream encoded with the joint residual block and the one or more syntax elements.

[0007] According to a third aspect of the present application, an apparatus for video decodingis provided, including: one or more processors; and a memory coupled to the one or more processors and configured to store instructions executable by the one or more processors, where the one or more processors, upon execution of the instructions, are configured to perform the method according to the first aspect.

[0008] According to a fourth aspect of the present application, a non-transitory computer-readable storage medium for storing computer-executable instructions is provided. When executed by one or more computer processors, the computer-executable instructions cause the one or more computer processors to perform the method according to the first aspect.

[0009] According to a fifth aspect of the present application, an apparatus for video encodingis provided, including: one or more processors; and a memory coupled to the one or more processors and configured to store instructions executable by the one or more processors, where the one or more processors, upon execution of the instructions, are configured to perform the method according to the second aspect.

[0010] According to a sixth aspect of the present application, a non-transitory computer-readable storage medium for storing computer-executable instructions is provided. When executed by one or more computer processors, the computer-executable instructions cause the one or more computer processors to perform the method according to the second aspect.

[0011] According to a seventh aspect of the present application, a non-transitory computer-readable storage medium having stored therein a bitstream comprising encoded video information to be decoded by the method according to the first aspect.

[0012] According to an eighth aspect of the present application, a non-transitory computer-readable storage medium having stored therein a bitstream comprising encoded video information generated by the method according to the second aspect.

[0013] According to a ninth aspect of the present application, provided is a method for storinga bitstream, including: performing the method for video encoding according to the second aspectAttorney Ref.: 186015.20231 to generate a bitstream; and storing the bitstream.

[0014] According to a tenth aspect of the present application, provided is a method fortransmitting a bitstream, including: performing the method for video encoding according to the second aspect to generate a bitstream; and transmitting the bitstream.

[0015] It is to be understood that both the foregoing general description and the followingdetailed description are examples only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which are incorporated in and constitute a part of thisspecification, illustrate examples consistent with the present disclosure and, together with the description, serve to explain the principles of the disclosure.

[0017] FIG. 1 is a block diagram illustrating an exemplary system for encoding and decodingvideo blocks in accordance with some implementations of the present disclosure.

[0018] FIG. 2 is a block diagram illustrating an exemplary video encoder in accordance withsome implementations of the present disclosure.

[0019] FIG. 3 is a block diagram illustrating an exemplary video decoder in accordance withsome implementations of the present disclosure.

[0020] FIGS. 4A through 4E are block diagrams illustrating how a frame is recursivelypartitioned into multiple video blocks of different sizes and shapes in accordance with some implementations of the present disclosure.

[0021] FIG.5 is a diagram illustrating a computing environment coupled with a user interface,according to some implementations of the present disclosure.

[0022] FIG. 6 is a flow chart illustrating a video decoding method according to someimplementations of the present disclosure.

[0023] FIG. 7 is a flow chart illustrating a video encoding method according to someimplementations of the present disclosure. DETAILED DESCRIPTION

[0024] Reference will now be made in detail to specific implementations, examples of whichare illustrated in the accompanying drawings. In the following detailed description, numerous non- limiting specific details are set forth in order to assist in understanding the subject matter presented herein. But various alternatives may be used without departing from the scope of claims and the subject matter may be practiced without these specific details. For example, the subject matterAttorney Ref.: 186015.20231 presented herein can be implemented on many types of electronic devices with digital video capabilities.

[0025] It should be illustrated that the terms “first,” “second,” and the like used in thedescription, claims of the present disclosure, and the accompanying drawings are used to distinguish objects, and not used to describe any specific order or sequence. It should be understood that the data used in this way may be interchanged under an appropriate condition, such that the embodiments of the present disclosure described herein may be implemented in orders besides those shown in the accompanying drawings or described in the present disclosure.

[0026] FIG. 1 is a block diagram illustrating an exemplary system 10 for encoding anddecoding video blocks in parallel in accordance with some implementations of the present disclosure. As shown in FIG. 1, the system 10 includes a source device 12 that generates and encodes video data to be decoded at a later time by a destination device 14. The source device 12 and the destination device 14 may comprise any of a wide variety of electronic devices, including cloud servers, server computers, desktop or laptop computers, tablet computers, smart phones, set- top boxes, digital televisions, cameras, display devices, digital media players, video gaming consoles, video streaming device, or the like. In some implementations, the source device 12 and the destination device 14 are equipped with wireless communication capabilities.

[0027] As shown in FIG. 1, the source device 12 includes a video source 18, a video encoder20 and an output interface 22. The video source 18 may include a source such as a video capturing device, e.g., a video camera, a video archive containing previously captured video, a video feeding interface to receive video from a video content provider, and / or a computer graphics system for generating computer graphics data as the source video, or a combination of such sources.

[0028] The captured, pre-captured, or computer-generated video may be encoded by the videoencoder 20. The encoded video data may comprise a sequence of pictures, each of which may comprise one or more sample arrays, for example, luma (Y) only for monochrome; luma and two chroma in YCbCr or YCgCo domain; or green, blue, and red in GBR (also known as RGB) domain. For convenience of notation and terminology in this application, in some embodiments, variables and terms associated with each set of three sample arrays may be referred to as luma and chroma, where the two chroma arrays may be referred to as Cb and Cr, regardless of the actual color representation method in use. The video data may be in a chroma format of 4:0:0, 4:2:0, 4:2:2, or 4:4:4, but the present application is not limited thereto. A bit depth BitDepth of samples of sampleAttorney Ref.: 186015.20231 arrays may be an integer in a range of 8 to 16. For example, a vlaue of BitDepth may be 8, 9, 10, 11, 12, 13, 14, 15 or 16. It should be illustrated that the value of BitDepth is not limited thereto, and may be any other value proposed in the future.

[0029] The encoded video data may be transmitted directly to the destination device 14through the output interface 22 of the source device 12 via a link 16. The output interface 22 may include a modem and / or a transmitter. The link 16 may comprise any type of wireless communication medium or device and / or any type of wired communication medium or device capable of transmitting the encoded video data from the source device 12 to the destination device 14. The encoded video data may also (or alternatively) be stored onto a storage device 32 for later access by the destination device 14 via for example an input interface 28 or by other devices, for decoding and / or playback. The storage device 32 may include any of a variety of distributed or locally accessed data storage media such as a hard drive, Blu-ray discs, Digital Versatile Disks (DVDs), Compact Disc Read-Only Memories (CD-ROMs), flash memory, volatile or non-volatile memory, or any other suitable digital storage media for storing the encoded video data.

[0030] The destination device 14 includes the input interface 28, a video decoder 30, and adisplay device 34. The input interface 28 may include a receiver and / or a modem and receive the encoded video data over the link 16. Alternatively, the destination device 14 may access the stored video data from the storage device 32 via streaming, downloading or a combination of both. The encoded video data may include a variety of syntax elements generated by the video encoder 20 for use by the video decoder 30 in decoding the video data. The display device 34 may be an integrated display device or an external display device that is configured to communicate with the destination device 14, and may display the decoded video data to a user.

[0031] The video encoder 20 and the video decoder 30 may operate (for example, encode anddecode video data) according to proprietary or industry standards, such as Versatile Video Coding (VVC), Joint Exploration test Model (JEM), High-Efficiency Video Coding (HEVC / H.265), Advanced Video Coding (AVC / H.264), Moving Picture Expert Group (MPEG) coding, or extensions of such standards. It should be understood that the present application is not limited to a specific video encoding / decoding standard, and may be applicable to other current and future video encoding / decoding standards.

[0032] The video encoder 20 and the video decoder 30 each may be implemented as any of avariety of suitable encoder and / or decoder circuitry, such as one or more microprocessors, DigitalAttorney Ref.: 186015.20231 Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), discrete logic, software, hardware, firmware or any combinations thereof. When implemented partially in software, an electronic device may store instructions for the software in a suitable, non-transitory computer-readable medium and execute the instructions in hardware using one or more processors to perform the video encoding / decoding operations disclosed in the present disclosure. Each of the video encoder 20 and the video decoder 30 may be included in one or more encoders or decoders, either of which may be integrated as part of a combined encoder / decoder (CODEC) in a respective device.

[0033] In some implementations, at least a part of components of the source device 12 and / orthe destination device 14 (for example, components shown in FIG.1, FIG.2 and / or FIG.3) may operate in a cloud computing service network which may provide software, platforms, and / or infrastructure, such as Software as a Service (SaaS), Platform as a Service (PaaS), or Infrastructure as a Service (IaaS). In some implementations, one or more components in the source device 12 and / or the destination device 14 which are not included in the cloud computing service network may be provided in one or more client devices, and the one or more client devices may communicate with server computers in the cloud computing service network through a wireless or wired communication network. In an embodiment, at least a part of operations described herein may be implemented as cloud-based services provided by one or more server computers which are implemented by the at least a part of the components of the source device 12 and / or the destination device 14 in the cloud computing service network; and one or more other operations described herein may be implemented by the one or more client devices. In some implementations, the cloud computing service network may be a private cloud, a public cloud, or a hybrid cloud. The terms such as “cloud,” “cloud computing,” “cloud-based” etc. herein may be used interchangeably as appropriate without departing from the scope of the present disclosure. It should be understood that the present disclosure is not limited to be implemented in the cloud computing service network described above. Instead, the present disclosure may also be implemented in any other type of computing environments currently known or developed in the future.

[0034] FIG. 2 is a block diagram illustrating an exemplary video encoder 20 in accordancewith some implementations described in the present application.

[0035] As shown in FIG.2, the video encoder 20 includes a video data memory 40, a predictionprocessing unit 41, a Decoded Picture Buffer (DPB) 64, a summer 50, a transform processing unitAttorney Ref.: 186015.20231 52, a quantization unit 54, and an entropy encoding unit 56. The prediction processing unit 41 further includes a motion estimation unit 42, a motion compensation unit 44, a partition unit 45, an intra prediction processing unit 46, and an Intra Block Copy (IBC) unit 48. In some implementations, the video encoder 20 also includes an inverse quantization unit 58, an inverse transform processing unit 60, and a summer 62 for video block reconstruction. An in-loop filter 63, such as a deblocking filter, may be positioned between the summer 62 and the DPB 64 to filter block boundaries to remove blockiness artifacts from reconstructed video. Another in-loop filter, such as Sample Adaptive Offset (SAO) filter, Cross Component Sample Adaptive Offset (CCSAO) filter and / or Adaptive in-Loop Filter (ALF), may also be used in addition to the deblocking filter to filter an output of the summer 62. It should be illustrated that for the CCSAO technique, the present application is not limited to the embodiments described herein, and instead, the application may be applied to a situation where an offset is selected for a sample of any of a luma component and two chroma components (which may represent Y, Cb and Cr in YCbCr domain; Y, Cg and Co in YCgCo domain; or G, B and R in RGB domain for convenience of notation and terminology in this application as described above) according to one or more samples of any other of the luma component and the two chroma components to modify the sample of said any component based on the selected offset. Alternatively, there is also provided an SAO technique which is substantially the same as the CCSAO technique, except that for the SAO technique, an offset is selected for a sample of any of a luma component and two chroma components according to one or more samples of said any component to modify the sample of said any component based on the selected offset. Further, it should also be illustrated that a first component mentioned herein may be any of the luma component and the two chroma components, a second component mentioned herein may be any other of the luma component and the two chroma components, and a third component mentioned herein may be a remaining one of the luma component and the two chroma components. In some examples, the in-loop filters may be omitted, and the decoded video block may be directly provided by the summer 62 to the DPB 64. The video encoder 20 may take the form of a fixed or programmable hardware unit or may be divided among one or more of the illustrated fixed or programmable hardware units.

[0036] The video data memory 40 may store video data to be encoded by the components ofthe video encoder 20. The video data in the video data memory 40 may be obtained, for example, from the video source 18 as shown in FIG.1. The DPB 64 is a buffer that stores reference videoAttorney Ref.: 186015.20231 data (for example, reference frames or pictures) for use in encoding video data by the video encoder 20. The video data memory 40 and the DPB 64 may be formed by any of a variety of memory devices. In various examples, the video data memory 40 may be on-chip with other components of the video encoder 20, or off-chip relative to those components. It should be noted that the term “frame” may be used as synonyms for the term “image” or “picture” in the field of video coding.

[0037] As shown in FIG. 2, after receiving the video data, the partition unit 45 partitions thevideo data into video blocks. This partitioning may also include partitioning a video frame into slices, tiles (for example, sets of video blocks), or other larger Coding Units (CUs) according to predefined splitting structures such as a Quad-Tree (QT) structure associated with the video data. The video frame is or may be regarded as a two-dimensional array or matrix of samples with sample values. A sample in the array may also be referred to as a pixel or a pel. A number of samples in horizontal and vertical directions (or axes) of the array or picture define a size and / or a resolution of the video frame. The video frame may be divided into multiple video blocks by, for example, using QT partitioning. The video block again is or may be regarded as a two-dimensional array or matrix of samples with sample values, although of smaller dimension than the video frame. A number of samples in horizontal and vertical directions (or axes) of the video block define a size of the video block. The video block may further be partitioned into one or more block partitions or sub-blocks (which may form again blocks) by, for example, iteratively using QT partitioning, Binary-Tree (BT) partitioning or Triple-Tree (TT) partitioning or any combination thereof. It should be noted that the term “block” or “video block” as used herein may be a portion, in particular a rectangular (square or non-square) portion, of a frame or a picture. With reference, for example, to HEVC and VVC, the block or video block may be or correspond to a Coding Tree Unit (CTU), a CU, a Prediction Unit (PU) or a Transform Unit (TU) and / or may be or correspond to a corresponding block, e.g. a Coding Tree Block (CTB), a Coding Block (CB), a Prediction Block (PB) or a Transform Block (TB) and / or to a sub-block.

[0038] The prediction processing unit 41 may select one of a plurality of possible predictivecoding modes, such as one of a plurality of intra or inter predictive coding modes, for the current video block based on error results (e.g., coding rate and the level of distortion). The prediction processing unit 41 may provide the resulting intra or inter prediction coded block to the summer 50 to generate a residual block and to the summer 62 to reconstruct the encoded block for use asAttorney Ref.: 186015.20231 part of a reference frame subsequently. The prediction processing unit 41 also provides at least one of syntax elements, such as motion vectors, intra or inter mode indicators, partition information, and other such syntax information, to the entropy encoding unit 56.

[0039] In order to select an appropriate intra predictive coding mode for the current videoblock, the intra prediction processing unit 46 may perform intra predictive coding of the current video block relative to one or more neighbor blocks in the same frame as the current block to be coded to provide spatial prediction. The motion estimation unit 42 and the motion compensation unit 44 perform inter predictive coding of the current video block relative to one or more predictive blocks in one or more reference frames to provide temporal prediction. The video encoder 20 may perform multiple coding passes, e.g., to select an appropriate coding mode for each block of video data.

[0040] In some implementations, the motion estimation unit 42 generates a motion vector ofthe current block in a motion estimation process according to a predetermined pattern within a sequence of video frames. The motion vector may indicate displacement of a video block within a current frame relative to a predictive block within a reference frame relative to the current block being coded within the current frame The predetermined pattern may designate video frames in the sequence as P frames or B frames. In some implementations, a Motion Vector Predictor (MVP) of the current block which may be determined from motion information of spatially neighboring blocks and / or temporally co-located blocks of the current block is subtracted from an actual motion vector of the current block to produce a Motion Vector Difference (MVD) for the current block. Then, instead of encoding, into the video bitstream, the actual motion vector of the current block, information of the MVP and MVD may be encoded into the video bitstream. The IBC unit 48 may determine vectors, e.g., block vectors, for IBC coding in a manner similar to the determination of motion vectors by the motion estimation unit 42 for inter prediction, or may utilize the motion estimation unit 42 to determine the block vector. It is noted that an IBC mode may be regarded as either an intra prediction mode or a prediction mode other than the intra prediction mode and an inter prediction mode.

[0041] A predictive block for the video block may be or may correspond to a block or areference block of a reference frame that is deemed as closely matching the video block to be coded in terms of pixel difference, which may be determined by Sum of Absolute Difference (SAD), Sum of Square Difference (SSD), or other difference metrics. In some implementations,Attorney Ref.: 186015.20231 the video encoder 20 may calculate values for sub-integer pixel positions of reference frames stored in the DPB 64. For example, the video encoder 20 may interpolate values of one-quarter pixel positions, one-eighth pixel positions, or other fractional pixel positions of the reference frame. Therefore, the motion estimation unit 42 may perform a motion search relative to the full pixel positions and fractional pixel positions and output a motion vector with fractional pixel precision.

[0042] The motion estimation unit 42 determines motion vector information for a video blockin an inter prediction coded frame by comparing the position of the video block to the position of a predictive block of a reference frame selected from a first reference frame list (List 0) or a second reference frame list (List 1), each of which identifies one or more reference frames stored in the DPB 64. The motion estimation unit 42 sends the determined motion vector information to the motion compensation unit 44 and then to the entropy encoding unit 56.

[0043] Motion compensation, performed by the motion compensation unit 44, may involvefetching or generating the predictive block based on the motion vector information determined by the motion estimation unit 42. Upon receiving the motion vector information for the current video block, the motion compensation unit 44 may locate a predictive block to which a motion vector points in one of the reference frame lists, retrieve the predictive block from the DPB 64, and forward the predictive block to the summer 50. The motion compensation unit 44 may also generate syntax elements associated with the video blocks of a video frame for use by the video decoder 30 in decoding the video blocks of the video frame. The syntax elements may include, for example, syntax elements defining the motion vector used to identify the predictive block, any flags indicating the prediction mode, or any other syntax information described herein. Note that the motion estimation unit 42 and the motion compensation unit 44 may be highly integrated, but are illustrated separately for conceptual purposes.

[0044] In some implementations, the IBC unit 48 may generate vectors and fetch predictiveblocks in a manner similar to that described above in connection with the motion estimation unit 42 and the motion compensation unit 44, but with the predictive blocks being in the same frame as the current block being coded and with the vectors being referred to as block vectors as opposed to motion vectors.

[0045] In other examples, the IBC unit 48 may use the motion estimation unit 42 and themotion compensation unit 44, in whole or in part, to perform such functions for IBC prediction according to the implementations described herein. In either case, for Intra block copy, a predictiveAttorney Ref.: 186015.20231 block may be a block that is deemed as closely matching the block to be coded, in terms of pixel difference, which may be determined by SAD, SSD, or other difference metrics, and identification of the predictive block may include calculation of values for sub-integer pixel positions.

[0046] The intra prediction processing unit 46 may intra-predict a current video block, as analternative to the inter-prediction performed by the motion estimation unit 42 and the motion compensation unit 44, or the intra block copy prediction performed by the IBC unit 48, as described above. In particular, the intra prediction processing unit 46 may determine an intra prediction mode to encode a current block. The intra prediction processing unit 46 may provide information indicative of the selected intra-prediction mode for the block to the entropy encoding unit 56. The entropy encoding unit 56 may encode the information indicating the selected intra-prediction mode in the bitstream.

[0047] After the prediction processing unit 41 determines the predictive block for the currentvideo block, the summer 50 forms a residual block by subtracting pixel values of the predictive block from the pixel values of the current video block, forming pixel difference values. The pixel difference values may include luma or chroma component differences or both. The residual video data in the residual block may be included in one or more TUs and is provided to the transform processing unit 52. The transform processing unit 52 transforms the residual video data into residual transform coefficients using one or more transforms, such as a Discrete Cosine Transform (DCT) or a conceptually similar transform.

[0048] The transform processing unit 52 may send the resulting transform coefficients to thequantization unit 54. The quantization unit 54 quantizes the transform coefficients to further reduce the bit rate. The quantization process may also reduce the bit depth associated with some or all of the coefficients. The degree of quantization may be modified by adjusting a quantization parameter. In some examples, the quantization unit 54 may then perform a scan of a matrix including the quantized transform coefficients. Alternatively, the entropy encoding unit 56 may perform the scan.

[0049] Following quantization, the entropy encoding unit 56 entropy encodes the quantizedtransform coefficients into a video bitstream using, e.g., Context Adaptive Variable Length Coding (CAVLC), Context Adaptive Binary Arithmetic Coding (CABAC), Syntax-based context-adaptive Binary Arithmetic Coding (SBAC), Probability Interval Partitioning Entropy (PIPE) coding or another entropy encoding methodology or technique. The encoded bitstream may then be transmitted to the video decoder 30 as shown in FIG. 1, or archived in the storage device 32 asAttorney Ref.: 186015.20231 shown in FIG.1 for later transmission to or retrieval by the video decoder 30. The entropy encoding unit 56 may also entropy encode the motion vectors and the other syntax elements for the current video frame.

[0050] The inverse quantization unit 58 and the inverse transform processing unit 60 applyinverse quantization and inverse transformation, respectively, to reconstruct the residual block in the pixel domain for generating a reference block for prediction of other video blocks.

[0051] As noted above, the motion compensation unit 44 may generate a motion compensatedpredictive block from one or more reference blocks of the frames stored in the DPB 64. The motion compensation unit 44 may also apply one or more interpolation filters to the predictive block to calculate sub-integer pixel values for use in motion estimation.

[0052] VVC supports the joint coding of chroma residual (JCCR) tool where the chromaresiduals are coded jointly. When the JCCR mode is activated for the current chroma TU, only one single joint chroma residual block is signalled, and residual block for Cb (resCb) and residual block for Cr (resCr) are derived. More details are captured from JVET-V2002 as following.

[0053] Joint coding of chroma residuals (JCCR)

[0054] VVC supports the joint coding of chroma residual (JCCR) tool where the chromaresiduals are coded jointly. The usage (activation) of the JCCR mode is indicated by a TU-level flag tu_joint_cbcr_residual_flag and the selected mode is implicitly indicated by the chroma CBFs. The flag tu_joint_cbcr_residual_flag is present if either or both chroma CBFs for a TU are equal to 1. In the PPS and slice header, chroma QP offset values are signalled for the JCCR mode to differentiate from the usual chroma QP offset values signalled for regular chroma residual coding mode. These chroma QP offset values are used to derive the chroma QP values for some blocks coded using the JCCR mode. The JCCR mode has 3 sub-modes. When a corresponding JCCR sub- mode (sub-modes 2 in Table 1) is active in a TU, this chroma QP offset is added to the applied luma-derived chroma QP during quantization and decoding of that TU. For the other JCCR sub- modes (sub-modes 1 and 3 in Table 1), the chroma QPs are derived in the same way as for conventional Cb or Cr blocks. The reconstruction process of the chroma residuals (resCb and resCr) from the transmitted transform blocks is depicted in Table 1. When the JCCR mode is activated, one single joint chroma residual block (resJointC[x][y] in Table 1) is signalled, and residual block for Cb (resCb) and residual block for Cr (resCr) are derived considering information such as tu_cbf_cb, tu_cbf_cr, and CSign, which is a sign value specified in the slice header.Attorney Ref.: 186015.20231

[0055] At the side of the encoder, the joint chroma components are derived as explained in thefollowing. Depending on the mode (listed in the tables below), resJointC{1,2} are generated by the encoder as follows: If mode is equal to 2 (single residual with reconstruction Cb = C, Cr = CSign * C), the joint residual is determined according to resJointC[ x ][ y ] = ( resCb[ x ][ y ] + CSign * resCr[ x ][ y ] ) / 2 Otherwise, if mode is equal to 1 (single residual with reconstruction Cb = C, Cr = (CSign * C) / 2), the joint residual is determined according to resJointC[ x ][ y ] = ( 4 * resCb[ x ][ y ] + 2 * CSign * resCr[ x ][ y ] ) / 5 Otherwise (mode is equal to 3, i. e., single residual, reconstruction Cr = C, Cb = (CSign * C) / 2), the joint residual is determined according to

[0056] resJointC[ x ][ y ] = ( 4 * resCr[ x ][ y ] + 2 * CSign * resCb[ x ][ y ] ) / 5Table 1 Reconstruction of chroma residuals tu_cbf_cb tu_cbf_cr reconstruction of Cb and Cr residuals mode

[0057] In Table 1, the value CSign is a sign value (+1 or −1), which is specified in the sliceheader, resJointC[ ][ ] is the transmitted residual.

[0058] The three joint chroma coding sub-modes described above in Table 1 are only supportedin I slices. In P and B slices, only mode 2 is supported. Hence, in P and B slices, the syntax element tu_joint_cbcr_residual_flag is only present if both chroma cbfs are 1.

[0059] The JCCR mode can be combined with the chroma transform skip (TS) mode. To speedup the encoder decision, the JCCR transform selection depends on whether the independent coding of Cb and Cr components selects the DCT-2 or the TS as the best transform, and whether there are non-zero coefficients in independent chroma coding. Specifically, if one chroma component selects DCT-2 (or TS) and the other component is all zero, or both chroma components select DCT- 2 (or TS), then only DCT-2 (or TS) will be considered in JCCR encoding. Otherwise, if oneAttorney Ref.: 186015.20231 component selects DCT-2 and the other selects TS, then both DCT-2 and TS will be considered in JCCR encoding.

[0060] The summer 62 adds the reconstructed residual block to the predictive block producedto produce a reference block for storage in the DPB 64.

[0061] FIG. 3 is a block diagram illustrating an exemplary video decoder 30 in accordancewith some implementations of the present application. The video decoder 30 includes a video data memory 79, an entropy decoding unit 80, a prediction processing unit 81, an inverse quantization unit 86, an inverse transform processing unit 88, a summer 90, and a DPB 92. The prediction processing unit 81 includes a motion compensation unit 82, an intra prediction unit 84, and an IBC unit 85. The video decoder 30 may perform a decoding process generally reciprocal to the encoding process described above with respect to the video encoder 20 in connection with FIG. 2. For example, the motion compensation unit 82 may generate prediction data based on motion vectors received from the entropy decoding unit 80, while the intra-prediction unit 84 may generate prediction data based on intra-prediction mode indicators received from the entropy decoding unit 80.

[0062] In some examples, a unit of the video decoder 30 may be tasked to perform theimplementations of the present disclosure. Also, in some examples, the implementations of the present disclosure may be divided among one or more of the units of the video decoder 30.

[0063] The video data memory 79 may store video data, such as an encoded video bitstream,to be decoded by the other components of the video decoder 30. The video data stored in the video data memory 79 may be obtained, for example, from the storage device 32, from a local video source, such as a camera, via wired or wireless network communication of video data, or by accessing physical data storage media (e.g., a flash drive or hard disk). The video data memory 79 may include a Coded Picture Buffer (CPB) that stores encoded video data from an encoded video bitstream. The DPB 92 of the video decoder 30 stores reference video data for use in decoding video data by the video decoder 30. The video data memory 79 and the DPB 92 may be formed by any of a variety of memory devices, such as dynamic random access memory (DRAM), including Synchronous DRAM (SDRAM), Magneto-resistive RAM (MRAM), Resistive RAM (RRAM), or other types of memory devices. In some examples, the video data memory 79 may be on-chip with other components of the video decoder 30, or off-chip relative to those components.

[0064] During the decoding process, the video decoder 30 receives an encoded video bitstreamAttorney Ref.: 186015.20231 that represents video blocks of an encoded video frame and associated syntax elements. The video decoder 30 may receive the syntax elements at the video frame level and / or the video block level. The entropy decoding unit 80 entropy decodes the bitstream to generate quantized coefficients, motion vector information or intra-prediction mode indicators, and other syntax elements. The entropy decoding unit 80 then forwards the motion vectors or intra-prediction mode indicators and other syntax elements to the prediction processing unit 81.

[0065] When the video frame is coded as an intra predictive coded (I) frame or for intra codedpredictive blocks in other types of frames, the intra prediction unit 84 may generate prediction data for a video block of the current video frame based on a signaled intra prediction mode and reference data from previously decoded blocks of the current frame.

[0066] When the video frame is coded as an inter-predictive coded (i.e., B or P) frame, themotion compensation unit 82 produces one or more predictive blocks for a video block of the current video frame based on the motion vector information and other syntax elements received from the entropy decoding unit 80. Each of the predictive blocks may be produced from a reference frame within one of the reference frame lists. The video decoder 30 may construct the reference frame lists, List 0 and List 1, using default construction techniques based on reference frames stored in the DPB 92.

[0067] In some examples, when the video block is coded according to the IBC mode describedherein, the IBC unit 85 produces predictive blocks for the current video block based on block vector information and other syntax elements received from the entropy decoding unit 80. The predictive blocks may be within a reconstructed region of the same picture as the current video block defined by the video encoder 20.

[0068] The motion compensation unit 82 and / or the IBC unit 85 determines predictioninformation for a video block of the current video frame by parsing the vector information and other syntax elements, and then uses the prediction information to produce the predictive blocks for the current video block. For example, the motion compensation unit 82 uses some of the received syntax elements to determine a prediction mode used to code video blocks of the video frame, an inter prediction frame type (e.g., B or P), construction information for one or more of the reference frame lists for the frame, motion vectors for each inter predictive encoded video block of the frame, inter prediction status for each inter predictive coded video block of the frame, and other information to decode the video blocks in the current video frame.Attorney Ref.: 186015.20231

[0069] Similarly, the IBC unit 85 may use some of the received syntax elements, e.g., a flag,to determine that the current video block was predicted using the IBC mode, construction information of which video blocks of the frame are within the reconstructed region and should be stored in the DPB 92, block vectors for each IBC predicted video block of the frame, IBC prediction status for each IBC predicted video block of the frame, and other information to decode the video blocks in the current video frame.

[0070] The motion compensation unit 82 may also perform interpolation using theinterpolation filters as used by the video encoder 20 during encoding of the video blocks to calculate interpolated values for sub-integer pixels of reference blocks. In this case, the motion compensation unit 82 may determine the interpolation filters used by the video encoder 20 from the received syntax elements and use the interpolation filters to produce predictive blocks.

[0071] Like the process of choosing a predictive block in a reference frame during inter-frameprediction of a video block, a set of rules needs to be adopted by both the video encoder 20 and the video decoder 30 for constructing a motion vector candidate list (also known as a “merge list”) for a current block using those potential candidate motion vectors associated with spatially neighboring blocks and / or temporally co-located blocks of the current block and then selecting one member from the motion vector candidate list as a motion vector predictor for the current block. By doing so, there is no need to transmit the motion vector candidate list itself from the video encoder 20 to the video decoder 30 and an index of the selected motion vector predictor within the motion vector candidate list is sufficient for the video encoder 20 and the video decoder 30 to use the same motion vector predictor within the motion vector candidate list for encoding and decoding the current block.

[0072] The inverse quantization unit 86 inverse quantizes the quantized transform coefficientsprovided in the bitstream and entropy decoded by the entropy decoding unit 80 using the same quantization parameter calculated by the video encoder 20 for each video block in the video frame. The inverse transform processing unit 88 applies an inverse transform, e.g., an inverse DCT, an inverse integer transform, or a conceptually similar inverse transform process, to the transform coefficients in order to reconstruct the residual blocks in the pixel domain.

[0073] The summer 90 reconstructs decoded video block for the current video block bysumming the residual block from the inverse transform processing unit 88 and a corresponding predictive block. An in-loop filter 91 such as deblocking filter, SAO filter, CCSAO filter and / orAttorney Ref.: 186015.20231 ALF may be positioned between the summer 90 and the DPB 92 to further process the decoded video block. In some examples, the in-loop filter 91 may be omitted, and the decoded video block may be directly provided by the summer 90 to the DPB 92. The decoded video blocks in a given frame are then stored in the DPB 92, which stores reference frames used for subsequent motion compensation of next video blocks. The DPB 92, or a memory device separate from the DPB 92, may also store decoded video for later presentation on a display device, such as the display device 34 of FIG.1.

[0074] In a typical video coding process, a video sequence typically includes an ordered set offrames or pictures. Each frame may include three sample arrays, denoted SL, SCb, and SCr. SL is a two-dimensional array of luma samples. SCb is a two-dimensional array of Cb chroma samples. SCr is a two-dimensional array of Cr chroma samples. In other instances, a frame may be monochrome and therefore includes only one two-dimensional array of luma samples.

[0075] As shown in FIG. 4A, the video encoder 20 (or more specifically the partition unit 45)generates an encoded representation of a frame by first partitioning the frame into a set of CTUs. A video frame may include an integer number of CTUs ordered consecutively in a raster scan order from left to right and from top to bottom. Each CTU is a largest logical coding unit and the width and height of the CTU are signaled by the video encoder 20 in a sequence parameter set, such that all the CTUs in a video sequence have the same size being one of 128×128, 64×64, 32×32, and 16×16. But it should be noted that the present application is not necessarily limited to a particular size. As shown in FIG.4B, each CTU may comprise one CTB of luma samples, two corresponding CTBs of chroma samples, and syntax elements used to code the samples of the CTBs. The syntax elements describe properties of different types of units of a coded block of pixels and how the video sequence can be reconstructed at the video decoder 30, including inter or intra prediction, intra prediction mode, motion vectors, and / or other parameters. In monochrome pictures or pictures having three separate color planes, a CTU may comprise a single CTB and syntax elements used to code the samples of the CTB. A CTB may be an NxN block of samples.

[0076] To achieve a better performance, the video encoder 20 may recursively perform treepartitioning such as binary-tree partitioning, ternary-tree partitioning, quad-tree partitioning or a combination thereof on the CTBs of the CTU and divide the CTU into smaller CUs. As depicted in FIG.4C, the 64x64 CTU 400 is first divided into four smaller CUs, each having a block size of 32x32. Among the four smaller CUs, CU 410 and CU 420 are each divided into four CUs of 16x16Attorney Ref.: 186015.20231 by block size. The two 16x16 CUs 430 and 440 are each further divided into four CUs of 8x8 by block size. FIG. 4D depicts a quad-tree data structure illustrating the end result of the partition process of the CTU 400 as depicted in FIG.4C, each leaf node of the quad-tree corresponding to one CU of a respective size ranging from 32x32 to 8x8. Like the CTU depicted in FIG.4B, each CU may comprise a CB of luma samples and two corresponding CBs of chroma samples, and syntax elements used to code the samples of the CBs. In monochrome pictures or pictures having three separate color planes, a CU may comprise a single CB and syntax structures used to code the samples of the CB. It should be noted that the quad-tree partitioning depicted in FIGS.4C and 4D is only for illustrative purposes and one CTU can be split into CUs to adapt to varying local characteristics based on quad / ternary / binary-tree partitions. In the multi-type tree structure, one CTU is partitioned by a quad-tree structure and each quad-tree leaf CU can be further partitioned by a binary and / or ternary tree structure. As shown in FIG.4E, there are five possible partitioning types of a CB having a width W and a height H, i.e., quaternary partitioning, horizontal binary partitioning, vertical binary partitioning, horizontal ternary partitioning, and vertical ternary partitioning.

[0077] In some implementations, the video encoder 20 may further partition a CB of a CU intoone or more MxN PBs. A PB is a rectangular (square or non-square) block of samples on which the same prediction, inter, intra etc., is applied. A PU of a CU may comprise a PB of luma samples, two corresponding PBs of chroma samples, and syntax elements used to predict the PBs. In monochrome pictures or pictures having three separate color planes, a PU may comprise a single PB and syntax structures used to predict the PB. The video encoder 20 may generate predictive luma, Cb, and Cr blocks for luma, Cb, and Cr PBs of each PU of the CU.

[0078] Furthermore, as illustrated in FIG. 4C, the video encoder 20 may use quad-treepartitioning to decompose the luma, Cb, and Cr residual blocks of a CU into one or more luma, Cb, and Cr transform blocks respectively. A transform block is a rectangular (square or non-square) block of samples on which the same transform is applied. A TU of a CU may comprise a TB of luma samples, two corresponding TBs of chroma samples, and syntax elements used to transform the TBs. Thus, each TU of a CU may be associated with a TB, a Cb TB, and a Cr TB. In some examples, the luma TB associated with the TU may be a sub-block of the CU's luma residual block. The Cb TB may be a sub-block of the CU's Cb residual block. The Cr TB may be a sub-block of the CU's Cr residual block. In monochrome pictures or pictures having three separate color planes,Attorney Ref.: 186015.20231 a TU may comprise a single TB and syntax structures used to transform the samples of the TB.

[0079] In the current JCCR design, a transmitted residual block is associated with two residualblocks of chroma components. The weights / relationship between the two chroma components are indicated by chroma cbf, as in Table 2. However, the residual relationship between Cb / Cr may be more complex than only 3 weights. Table 2 cbf_cb cbf_cr JCCR 0 JCCR 1 w = Cr / Cb mode

[0080] In this disclosure, multiple weights for joint coding of at least two color componentsare proposed, as shown in Table 3. At a side of an encoder, one or more residual blocks are transmitted, where each residual block is associated with at least two residual blocks of different color components. At a side of a decoder, the relationship / weights between two residual blocks are explicitly signaled by encoder, or implicitly derived from available prediction, reconstruction, or residual samples.

[0081] In some examples, encoders may explicitly signal weights: one residual block istransmitted for both Cb and Cr components, and one syntax element is signaled to indicate the respective weight Cr / Cb for each chroma TU. At the side of the decoder, the received residual block is directly applied for the Cb component, multiplied by the indicated weight and applied for the Cr component.Attorney Ref.: 186015.20231 Table 3 cbf_cb cbf_cr JCCR 0 JCCR 1 w = Cr / Cb modeg y p . g ghtsfrom -8, -4, -8 / 3, -2, -8 / 5, -4 / 3, -8 / 7, -1, -7 / 8, -¾, -5 / 8, -½, -3 / 8, -¼, -1 / 8. The sign (-) can be determined and signaled in the PH as in VVC, or included in the weight table and signaled per chroma TU. Table 4 Sign w 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15± Cr / Cb 2 1 / 2 1 / 8 / 8

[0083] At the side of encoder, to determine the best joint residuals that minimize MSEfor both Cb and Cr, following problem may be solved: ^^^^^^^^^^ = ^^ ∗ ^^^^^^^^^^Find ResJ, such that ^^^^^^[(^^^^^^^^^^ − ^^^^^^^^)2 + (^^^^^^^^^^ − ^^ ∗ ^^^^^^^^)2]−2 ∗ ^^^^^^^^^^ + 2 ∗ ^^^^^^^^ − 2^^ ∗ ^^^^^^^^^^ + 2^^2 ∗ ^^^^^^^^ = 0^^^^^^^^ + ^^2 ∗ ^^^^^^^^ = ^^^^^^^^^^ + ^^ ∗ ^^^^^^^^^^^^^^^^^^ = (^^^^^^^^^^ + ^^ ∗ ^^^^^^^^^^) / (1 + ^^2)

[0084] The followingavailable target original^^^^^^^^^^ and ^^^^^^^^^^ at the side of encoder. In some examples, wieght = Cr / Cb = 8 / 3, where the bestAttorney Ref.: 186015.20231 ^^^^^^^^ = (^^^^^^^^^^ +8 3∗ ^^^^^^^^^^) (64 ∗ ^^^ )2 =^^^^^^^ + 24 ∗ ^^^^^^^^^^Sign w 012 13 14 15± Cr / Cb 2 1 / 2 18 / 1 8 / 2 8 / 3 8 / 4 8 / 5 8 / 6 8 / 7 8 / 8 7 / 8 6 / 8 5 / 8 4 / 8 3 / 8 2 / 8 1 / 88 4 8 / 3 2 8 / 5 4 / 3 8 / 7 1 7 / 8 3 / 4 5 / 8 1 / 2 3 / 8 1 / 4 1 / 8 +865+865, . ingweights on Cr, the weights may be applied on Cb or Cr to derive the other compoent residuals with the absolute weight values always less than 1. It is similar to VVC JCCR in Table 1.

[0086] In one or more examples, instead of weight indices 1~15, absolute weight values 8~1 / 8,which are always applied on Cr, weight indices 1~7 may indicate applying on Cb, with absolute weight values 1 / 8~7 / 8. Encoders or decoders may apply the transimitted joint residuals on one component, with another component absolute weight values less than 1. The approach may improve residual precision, as a finer joint residual is signaled.

[0087] In some examples, the weight indices may be signaled under Cb / Cr cbfs are both 1,with JCCR flag being 1. In this case, Cb / Cr cbfs are 01 or 10, and encoders don’t need to signal the JCCR flag (back to cbf orginal meaning, Cb / Cr blocks have no residuals).

[0088] FIG. 5 shows a computing environment 510 coupled with a user interface 550. Thecomputing environment 510 can be part of a data processing server. The computing environment 510 includes a processor 520, a memory 530, and an Input / Output (I / O) interface 540.

[0089] The processor 520 typically controls overall operations of the computing environment510, such as the operations associated with display, data acquisition, data communications, and image processing. The processor 520 may include one or more processors to execute instructions to perform all or some of the steps in the above-described methods. Moreover, the processor 520 may include one or more modules that facilitate the interaction between the processor 520 and other components. The processor may be a Central Processing Unit (CPU), a microprocessor, a single chip machine, a Graphical Processing Unit (GPU), or the like.

[0090] The memory 530 is configured to store various types of data to support the operationof the computing environment 510. The memory 530 may include predetermined software 532.Attorney Ref.: 186015.20231 Examples of such data includes instructions for any applications or methods operated on the computing environment 510, video datasets, image data, etc. The memory 530 may be implemented by using any type of volatile or non-volatile memory devices, or a combination thereof, such as a Static Random Access Memory (SRAM), an Electrically Erasable Programmable Read-Only Memory (EEPROM), an Erasable Programmable Read-Only Memory (EPROM), a Programmable Read-Only Memory (PROM), a Read-Only Memory (ROM), a magnetic memory, a flash memory, a magnetic or optical disk.

[0091] The I / O interface 540 provides an interface between the processor 520 and peripheralinterface modules, such as a keyboard, a click wheel, buttons, and the like. The I / O interface 540 can be coupled with an encoder and decoder.

[0092] FIG. 6 is a flowchart illustrating a video decoding method according to an example ofthe present disclosure. According to the video decoding method illustrated in FIG. 6, multiple weights for joint coding of at least two color components are provided.

[0093] In step 610, the processor 520, from the video decoder side, may determine whetherjoint residual coding of multiple color components is applied to a video block.

[0094] In step 620, the processor 520 may obtain one or more syntax elements indicating aweight associated with a first color component, in response to determining that the joint residual coding of multiple color components is applied to the video block.

[0095] In some examples, the weight may be explicitly signaled in a bitstream. As discussedabove, a decoder may receive an explicitly signaled weight form an encoder. For example, one syntax element may be signaled to indicate the respective weight Cr / Cb for each chroma TU.

[0096] In some examples, the processor 520 may obtain a joint residual block in response todetermining that the joint residual coding of multiple color components is applied to the video block, where the joint residual block is directly applied to obtain the second residual block and is determined, at the encoder side, by minimizing mean squared error between original residuals of the first and second color components. As discussed above, when Cr residual block is derived, the received joint residual block is directly applied for the Cb component to obtain a Cb residual block, and the Cb residual block is multiplied by the weight to obtain the Cr residual block. Furthermore, minimizing mean squared error between original residuals of the first and second color components, e.g., both Cb and Cr, will determine the best joint residuals / residual blocks ^^^^^^^^.

[0097] In some examples, the first color component is a Cb component and the second colorAttorney Ref.: 186015.20231 component is a Cr component, or the first color component is the Cr component and the second color component is the Cb component.

[0098] In some examples, the weight may include a weight value whose absolute value is lessthan one. For example, instead of always apply weights on Cr, weights may be applied on Cb or Cr, and the other component residuals that are derived have the absolute weight values always less than 1. Apply the transimitted joint residuals on one component, with another component absolute weight values less than 1 can improve residual precision, as a finer joint residual is signaled.

[0099] In some examples, the weight may further include a sign, and the weight value and thesign are signaled at different syntax levels. The sign (e.g., “–”) may be determined and signaled in the picture header (PH), as in VVC, or alternatively in the weight table and signaled per chroma transform unit (TU).

[0100] In some examples, the one or more syntax elements may include an index in apredefined weight table stored at the decoder, and the index indicates the weight selected from a plurality of predefined weights. The processor 520 may receive the index in response to determining that both chroma blocks have residuals. For example, when both chroma coded block flags (e.g., Cb and Cr cbfs) are equal to 1, it is determined that both chroma blocks, i.e., Cb / Cr blocks, have residuals. The predefined weight table may be a table as shown in Table 4. The weight indices may be signaled when both the Cb and Cr coded block flags are equal to 1, together with a JCCR flag set to 1. In contrast, when the Cb and Cr coded block flags indicate 0 and 1 or 1 and 0, the JCCR flag need not be signaled, and the coded block flags retain their original meaning that one of the Cb or Cr residual blocks is absent.

[0101] In step 630, the processor 520 may decode a second residual block of a second colorcomponent.

[0102] In step 640, the processor 520 may derive a first residual block of the first colorcomponent based on the one or more syntax elements and the second residual block.

[0103] As discussed above, when the Cr residual block is to be derived, the received jointresidual block is directly applied to obtain the Cb residual block, and the Cb residual block is then multiplied by the weight to derive the Cr residual block.

[0104] FIG. 7 is a flowchart illustrating a video encoding method according to an example ofthe present disclosure. The video encoding method corresponds to the video decoding method as shown in FIG.6.Attorney Ref.: 186015.20231

[0105] In step 710, the processor 520, from the video encoder side, may determine one or moresyntax elements indicating a weight associated with a first color component, where joint residual coding from multiple color components is applied to a video block, and the weight is selected from a plurality of predefined weights.

[0106] In step 720, the processor 520 may signal a joint residual block and the one or moresyntax elements indicating the weight associated with the first color component, where the joint residual block corresponds to a second color components, and the multiple color components comprise the first and second color components.

[0107] In some examples, the weight may be explicitly signaled in a bitstream. As discussedabove, an encoder may explicitly signal a weight. For example, one syntax element may be signaled to indicate the respective weight Cr / Cb for each chroma TU.

[0108] In some examples, the processor 520 may determine the joint residual block byminimizing mean squared error between original residuals of the first and second color components. As discussed above, minimizing mean squared error between original residuals of the first and second color components, e.g., both Cb and Cr, will determine the best joint residuals / residual blocks ^^^^^^^^.

[0109] In some examples, the first color component is a Cb component and the second colorcomponent is a Cr component, or the first color component is the Cr component and the second color component is the Cb component.

[0110] In some examples, the weight may include a weight value whose absolute value is lessthan one. For example, instead of always apply weights on Cr, weights may be applied on Cb or Cr, and the other component residuals that are derived have the absolute weight values always less than 1. Apply the transimitted joint residuals on one component, with another component absolute weight values less than 1 can improve residual precision, as a finer joint residual is signaled.

[0111] In some examples, the weight may further include a sign, and the weight value and thesign are signaled at different syntax levels. The sign (e.g., “–”) may be determined and signaled in the picture header (PH), as in VVC, or alternativelyin the weight table and signaled per chroma transform unit (TU).

[0112] In some examples, the one or more syntax elements may include an index in apredefined weight table stored at the encoder, and the index indicates the weight selected from a plurality of predefined weights. The processor 520 may signal the index when both chroma blocksAttorney Ref.: 186015.20231 have residuals, and joint residual coding of multiple color components is applied to a video block. For example, when both chroma coded block flags (e.g., Cb and Cr cbfs) are equal to 1, it is determined that both chroma blocks, i.e., Cb / Cr blocks, have residuals. The predefined weight table may be a table as shown in Table 4. The weight indices may be signaled when both the Cb and Cr coded block flags are equal to 1, together with a JCCR flag set to 1. In contrast, when the Cb and Cr coded block flags indicate 0 and 1 or 1 and 0, the JCCR flag need not be signaled, and the coded block flags retain their original meaning that one of the Cb or Cr residual blocks is absent.

[0113] In step 730, the processor 520 may transmit a bitstream encoded with the joint residualblock and the one or more syntax elements.

[0114] In an embodiment, there is also provided a non-transitory computer-readable storagemedium or a computer program product comprising a plurality of programs, for example, in the memory 530, executable by the processor 520, for performing the encoding or decoding method described above and / or storing a bitstream which is generated by the encoding method described above and / or is to be decoded by the decoding method described above. For example, the computer program product may include the non-transitory computer-readable storage medium. In one example, the plurality of programs may be executed by the processor 520 to receive (for example, from the video encoder 20 in FIG. 2) a bitstream or data stream including encoded video information (for example, video blocks representing encoded video frames, and / or associated one or more syntax elements, etc.), and may also be executed by the processor 520 to perform the decoding method described above according to the received bitstream or data stream. In another example, the plurality of programs may be executed by the processor 520 to perform the encoding method described above to encode video information (for example, video blocks representing video frames, and / or associated one or more syntax elements, etc.) into a bitstream or data stream, and may also be executed by the processor 520 to transmit the bitstream or data stream (for example, to the video decoder 30 in FIG.3) or store the bitstream or data stream. Alternatively, the non-transitory computer-readable storage medium or the computer program product may have stored therein the bitstream or data stream.

[0115] In an embodiment, there is provided a bitstream (for example, comprising encodedvideo information) which is generated by the encoding method described above and / or is to be decoded by the decoding method described above.

[0116] In an embodiment, there is also provided a computing device comprising one or moreAttorney Ref.: 186015.20231 processors (for example, the processor 520); and the non-transitory computer-readable storage medium or the memory 530 having stored therein a plurality of programs executable by the one or more processors, wherein the one or more processors, upon execution of the plurality of programs, are configured to perform the above-described methods. In an example, the one or more processors, upon execution of the plurality of programs, are configured to perform the above-described encoding method to generate a bitstream, and the computing device may further comprise a transmitter, configured to transmit the bitstream. In an alternative example, the one or more processors, upon execution of the plurality of programs, are configured to perform the above- described encoding method to generate a bitstream, and transmit or store the bitstream. In an example, the bitstream is to be decoded by the above-described decoding method.

[0117] In an embodiment, the computing environment 510 may be implemented with one ormore ASICs, DSPs, Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), FPGAs, GPUs, controllers, micro-controllers, microprocessors, or other electronic components, for performing the above methods.

[0118] In an embodiment, there is also provided a method for storing a bitstream, comprisingstoring the bitstream on a non-transitory computer-readable storage medium, wherein the bitstream is generated by the encoding method described above and / or is to be decoded by the decoding method described above. In an embodiment, there is also provided a method for storing a bitstream or a method for encoding video data, comprising: performing the encoding method described above to generate a bitstream, and storing the bitstream on a non-transitory computer-readable storage medium. In an example, the bitstream is to be decoded by the decoding method described above.

[0119] In an embodiment, there is also provided a method for transmitting a bitstream whichis generated by the encoding method described above and / or is to be decoded by the decoding method described above. In an embodiment, there is also provided a method for transmitting a bitstream or a method for encoding video data, comprising: performing the encoding method described above to generate a bitstream, and transmitting the bitstream to a decoder. In an example, the bitstream is to be decoded by the decoding method described above. In an embodiment, there is also provided a method for receiving a bitstream which is generated by the encoding method described above and / or is to be decoded by the decoding method described above.

[0120] The description of the present disclosure has been presented for purposes of illustrationAttorney Ref.: 186015.20231 and is not intended to be exhaustive or limited to the present disclosure. Many modifications, variations, and alternative implementations will be apparent to those of ordinary skill in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings.

[0121] Unless specifically stated otherwise, an order of steps of the method according to thepresent disclosure is only intended to be illustrative, and the steps of the method according to the present disclosure are not limited to the order specifically described above, but may be changed according to practical conditions. In addition, at least one of the steps of the method according to the present disclosure may be adjusted, combined or deleted according to practical requirements.

[0122] The examples were chosen and described in order to explain the principles of thedisclosure and to enable others skilled in the art to understand various implementations of the disclosure and to best utilize the underlying principles and various implementations with various modifications as are suited to the particular use contemplated. Therefore, it is to be understood that the scope of the disclosure is not to be limited to the specific examples of the implementations disclosed and that modifications and other implementations are intended to be included within the scope of the present disclosure.

Claims

Attorney Ref.: 186015.20231 WHAT IS CLAIMED IS:

1. A method for video decoding, comprising: determining, by a decoder, whether joint residual coding of multiple color components is applied to a video block; in response to determining that the joint residual coding of multiple color components is applied to the video block, obtaining, by the decode, one or more syntax elements indicating a weight associated with a first color component; decoding, by the decoder, a second residual block of a second color component; and deriving, by the decoder, a first residual block of the first color component based on the one or more syntax elements and the second residual block.

2. The method of claim 1, wherein the weight is explicitly signaled in a bitstream.

3. The method of claim 1, further comprising: in response to determining that the joint residual coding of multiple color components is applied to the video block, obtaining, by the decoder, a joint residual block, wherein the joint residual block is directly applied to obtain the second residual block of the second color component, and wherein the joint residual block is determined by minimizing mean squared error between original residuals of the first and second color components.

4. The method of claim 1, wherein the first color component is a Cb component and the second color component is a Cr component, or wherein the first color component is the Cr component and the second color component is the Cb component.

5. The method of claim 1, wherein the weight comprises a weight value, and the weight value has an absolute value less than one.

6. The method of claim 5, wherein the weight further comprises a sign, and the weight value and the sign are signaled at different syntax levels.Attorney Ref.: 186015.20231 7. The method of claim 1, wherein the one or more syntax elements comprises an index in a predefined weight table stored at the decoder, and the index indicates the weight selected from a plurality of predefined weights.

8. The method of claim 7, wherein receiving the one or more syntax elements indicating the weight associated with the first color component further comprising: in response to determining that both chroma blocks have residuals, or that both chroma coded block flags are equal to 1, receiving the index indicating the weight associated with the first color component.

9. A method for video encoding, comprising: determining, by an encode, one or more syntax elements indicating a weight associated with a first color component, wherein joint residual coding from multiple color components is applied to a video block, and wherein the weight is selected from a plurality of predefined weights; signaling, by the encoder, a joint residual block and the one or more syntax elements indicating the weight associated with the first color component, wherein the joint residual block corresponds to a second color components, and wherein the multiple color components comprise the first and second color components; and transmitting, by the encoder, a bitstream encoded with the joint residual block and the one or more syntax elements.

10. The method of claim 9, wherein signaling the one or more syntax elements indicating the weight associated with the first color component comprises: explicitly signaling the weight associated with the first color component in a bitstream.

11. The method of claim 9, further comprising: determining, by the encoder, the joint residual block by minimizing mean squared error between original residuals of the first and second color components.Attorney Ref.: 186015.20231 12. The method of claim 9, wherein the first color component is a Cb component and the second color component is a Cr component, or wherein the first color component is the Cr component and the second color component is the Cb component.

13. The method of claim 9, wherein the weight comprises a weight value having an absolute value less than one.

14. The method of claim 13, wherein the weight further comprises a sign, and the method further comprises: signaling, by the encoder, the weight value and the sign at different syntax levels.

15. The method of claim 9, wherein the one or more syntax elements comprises an index in a predefined weight table stored at the decoder, and the index indicates the weight selected from the plurality of predefined weights.

16. The method of claim 15, wherein signaling the one or more syntax elements indicating the weight associated with the first color component comprises: signaling the index indicating the weight associated with the first color component, wherein both chroma blocks have residuals or both chroma coded block flags are equal to 1, and wherein joint residual coding of multiple color components is applied to a video block.

17. An apparatus for video decoding, comprising: one or more processors; and a memory coupled to the one or more processors and configured to store instructions executable by the one or more processors, wherein the one or more processors, upon execution of the instructions, are configured to perform the method in any one of claims 1-8.Attorney Ref.: 186015.20231 18. A non-transitory computer-readable storage medium for storing computer-executable instructions that, when executed by one or more computer processors, cause the one or more computer processors to perform the method in any of claims 1-8.

19. An apparatus for video encoding, comprising: one or more processors; and a memory coupled to the one or more processors and configured to store instructions executable by the one or more processors, wherein the one or more processors, upon execution of the instructions, are configured to perform the method in any one of claims 9-16.

20. A non-transitory computer-readable storage medium for storing computer-executable instructions that, when executed by one or more computer processors, cause the one or more computer processors to perform the method in any of claims 9-16.

21. A non-transitory computer-readable storage medium having stored therein a bitstream comprising encoded video information to be decoded by the method in any of claims 1-8.

22. A non-transitory computer-readable storage medium having stored therein a bitstream comprising encoded video information generated by the method in any of claims 9-16.

23. A method for storing a bitstream, comprising: performing the method for video encoding according to any one of claims 9-16 to generate a bitstream; and, storing the bitstream.

24. A method for transmitting a bitstream, comprising: performing the method for video encoding according to any one of claims 9-16 to generate a bitstream; and, transmitting the bitstream.

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