TW202310623A - Method and apparatus of video coding - Google Patents

Abstract

Methods and apparatus for video encoding and decoding systems that utilize joint coding of multi-colour components are disclosed. At the video encoding side, a first residual block for the first colour block and a second residual block for the second colour block are determined. Whether a target condition is satisfied is determined, where the target condition belongs to a group comprising a first condition related to a number of non-zero quantized coefficients of a joint residual block. When the target condition is satisfied, joint multi-colour coding is disabled. When the target condition is not satisfied, joint multi-colour coding is enabled. Accordingly, no signalling is required to indicate if the joint multi-colour coding is activated when the target condition is satisfied.

Description

Video codec method and device

The invention relates to a video codec system. Specifically, the present invention relates to efficient joint coding and decoding of multi-color components in a video coding and decoding system.

Versatile video coding (VVC for short) is developed by ITU-T Video Coding Experts Group (VCEG for short) and ISO/IEC Moving Picture Experts Group (MPEG for short). The latest international video codec standard developed by the Joint Video Experts Team (JVET). This standard was published as an ISO standard in February 2021: ISO/IEC 23090-3:2021, Information technology – Coded representations for immersive media – Part 3: Multifunctional video codecs. VVC is based on its previous generation of High Efficiency Video Coding (HEVC) by adding more codec tools to improve codec efficiency and process 3-dimensional (3-dimensional, 3D) video signals. Various types of video sources.

FIG. 1A shows an example adaptive inter/intra video coding system incorporating loop processing. For intra prediction, the prediction data is based on previously coded video data in the current picture. For inter prediction 112 , motion estimation (ME) is performed at the encoder side and motion compensation (MC) is performed based on the ME result to provide prediction data derived from other pictures and motion data. A switch 114 selects intra prediction 110 or inter prediction 112 and the selected prediction is provided to an adder 116 to form a prediction error, also called a residual. The prediction error is then processed by Transform (T for short) 118 followed by Quantization (Q for short) 120 . The transformed and quantized residual is then encoded by entropy encoder 122 for inclusion in a video bitstream corresponding to the compressed video data. Then, the bitstream associated with the transform coefficients is paired with side information (such as motion and coding modes associated with intra- and inter-prediction) and other information (related to the in-loop filtering applied to the underlying image region Parameters associated with the device, etc.) packaging. As shown in FIG. 1A , side information associated with intra prediction 110 , inter prediction 112 and loop filter 130 is provided to entropy encoder 122 . When inter prediction mode is used, one or more reference pictures must also be reconstructed at the encoder. Therefore, the transformed and quantized residual is processed by Inverse Quantization (IQ) 124 and Inverse Transformation (IT) 126 to recover the residual. The residuals are then added back to the prediction data 136 at reconstruction (REC) 128 to reconstruct the video data. The reconstructed video data can be stored in the reference picture buffer 134 and used for prediction of other frames.

As shown in FIG. 1A, the input video data undergoes a series of processing in the encoding system. Due to a series of processes, the reconstructed video data from REC 128 may be subject to various impairments. Therefore, before the reconstructed video data is stored in the reference picture buffer 134, the loop filter 130 is usually applied to the reconstructed video data to improve the video quality. For example, a deblocking filter (deblocking filter, DF for short), a sample adaptive offset (Sample Adaptive Offset, SAO for short), and an adaptive loop filter (Adaptive Loop Filter, ALF for short) may be used. Loop filter information may need to be incorporated into the bitstream so that the decoder can correctly recover the required information. Therefore, the loop filter information is also provided to the entropy encoder 122 for incorporation into the bitstream. In FIG. 1A , loop filter 130 is applied to the reconstructed video before the reconstructed samples are stored in reference picture buffer 134 . The system in Figure 1A is intended to illustrate an example structure of a typical video encoder. It may correspond to a High Efficiency Video Coding (HEVC) system, VP8, VP9, H.264 or VVC.

The decoder can use similar or partly the same functional blocks as the encoder, except for transform 118 and quantization 120 since the decoder only needs inverse quantization 124 and inverse transform 126 . The decoder uses the entropy decoder 140 instead of the entropy encoder 122 to decode the video bitstream into quantized transform coefficients and required codec information (eg, ILPF information, intra prediction information and inter prediction information). Intra prediction 150 at the decoder side does not need to perform a mode search. Instead, the decoder only needs to generate intra prediction based on the intra prediction information received from the entropy decoder 140 . Furthermore, for inter prediction, the decoder only needs to perform motion compensation (MC 152 ) based on the intra prediction information received from entropy decoder 140 without motion estimation.

According to VVC, the input picture is divided into non-overlapping square block regions called Coding Tree units (CTU), similar to HEVC. Each CTU can be divided into one or more smaller-sized codec units (coding unit, CU for short). The resulting CU partition can be square or rectangular. In addition, VVC divides the CTU into a prediction unit (prediction unit, PU for short) as a unit to apply prediction processing, such as inter-frame prediction, intra-frame prediction, and the like.

The VVC standard combines various new codec tools, which further improves the codec efficiency compared with the HEVC standard. Among the various new codec tools, some have been adopted by the standard, and some have not. Among the new codec tools, a technique called Joint coding of chroma residual (JCCR) has been disclosed. A brief review of the JCCR follows.

Chroma Residual Union Codec ( Joint Coding of Chroma Residual , referred to as JCCR )

VVC (Adrian Browne, et al., "Algorithm description for Versatile Video Coding and Test Model 14 (VTM 14)", Joint Video Exploration Team (JVET) of ITU-T SG 16 WP 3 and ISO/IEC JTC 1/SC 29 /WG 11, 23rd Meeting, by teleconference, 7–16 July 2021, Document: W2002) supports the joint coding of chroma residual (JCCR) tool (section 3.5.7 of JVET-W2002) , where the chrominance residuals of the color components are jointly coded. The use (that is, enablement) of the JCCR mode is indicated by the TU-level flag tu_joint_cbcr_residual_flag, and the selected mode is implicitly indicated by the chroma codec block flag (coded block flag, cbf for short). The flag tu_joint_cbcr_residual_flag is present if one or both chroma cbfs of the TU are equal to 1. In the picture parameter set (Picture Parameter Set, referred to as PPS) and the fragment header, the chroma quantization parameter (referred to as QP) offset value is sent to the JCCR mode to distinguish it from the usual chroma residual codec mode. The chroma QP offset value. These chroma QP offset values are used to derive chroma QP values for some blocks coded by JCCR mode. The JCCR mode has 3 sub-modes. This chroma QP offset is added to the applied luma-derived chroma during quantization and decoding of the TU when the corresponding JCCR submode (i.e., submode 2 in Table 3-11) is enabled in the TU. Degree QP. For other JCCR submodes (i.e., submodes 1 and 3 in Table 3-11), chroma QPs are derived in the same way as regular Cb or Cr blocks. The reconstruction process of the chroma residuals (resCb and resCr) from the transmitted transform block is described in Table 3-11 of JVET-W2002. When JCCR mode is enabled, a single joint chroma residual block (resJointC[x][y] in Table 3-11) is sent, along with the Cb residual block (resCb) and the Cr residual block ( resCr) is derived taking into account information such as tu_cbf_cb, tu_cbf_cr and CSign, where CSign is the sign value specified in the fragment header.

On the encoder side, the derivation of the joint chroma components is described below. Depending on the mode, the encoder generates resJointC{1,2} as follows:

– If mode is equal to 2 (single residuals with reconstruction Cb = C, Cr = CSign * C), the joint residuals are determined according to: resJointC[ x ][ y ] = ( resCb[ x ][ y ] + CSign * resCr[ x ][ y ] ) / 2

– Otherwise, if mode equals 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 equal to 3, i.e. single residual, reconstructed Cr = C, Cb = (CSign * C)/2), the joint residual is determined by: resJointC[ x ][ y ] = (4 * resCr[ x ][ y ]+2 * CSign * resCb[ x ][ y ]) / 5

W2002 table 3-11- chroma residual refactor. CSign Values are symbolic values ( +1 or -1 ), specified in the fragment header, resJointC [ ][ ] is the transfer residual. tu_cbf_cb tu_cbf_cr Reconstruction of Cb and Cr residuals model 1 0 resCb[ x ][ y ] = resJointC[ x ][ y ] resCr[ x ][ y ] = (CSign * resJointC[ x ][ y ]) > > 1 1 1 1 resCb[ x ][ y ] = resJointC[ x ][ y ] resCr[ x ][ y ] = CSign * resJointC[ x ][ y ] 2 0 1 resCb[ x ][ y ] = ( CSign * resJointC[ x ][ y ] ) > > 1 resCr[ x ][ y ] = resJointC[ x ][ y ] 3

The three joint chroma codec submodes described in Table 3-11 above are only supported in I slices. In P and B segments, only mode 2 is supported. Therefore, in P and B slices, the syntax element tu_joint_cbcr_residual_flag is only present if both chroma cbfs are 1 (i.e. at least one non-zero coefficient is present in the block).

JCCR mode can be combined with chroma transform skip (TS) mode (more details on TS mode can be found in Section 3.9.3 of JVET-W2002). To speed up the encoder's decision, the choice of the JCCR transform depends on whether the independent encoding of the Cb and Cr components chooses DCT-2 or TS as the best transform, and whether there are non-zero coefficients in the independent chroma codec. Specifically, if one chroma component selects DCT-2 (or TS) and the other component is all zeros, or both chroma components select DCT-2 (or TS), then only DCT-2 will be considered in JCCR encoding 2 (or TS). Otherwise, if one component selects DCT-2 and the other selects TS, then both DCT-2 and TS will be considered in JCCR encoding.

Although the JCCR codec tool can improve codec efficiency, it needs to send a flag (jccr_flag) for each block. In some cases, this overhead information may even hurt the overall codec efficiency. Therefore, schemes need to be developed to maintain codec efficiency in all situations.

A method and apparatus for a video encoding and decoding system using joint encoding and decoding of multi-color components are disclosed. According to the method, at the video encoding side, input data comprising multi-color blocks of a video unit is received, wherein said multi-color blocks at least include a first color block corresponding to a first color component and a second color block corresponding to a second color component Two color blocks. The first residual block of the first color block is determined by using the first predictor. The second residual block of the second color block is determined by using the second predictor. determining whether a target condition is satisfied, wherein the target condition belongs to the group comprising a first condition associated with the number of non-zero quantized coefficients of the joint residual block or a second condition associated with the codec unit size of the multi-color block ; and the joint residual block is generated based on the first residual block and the second residual block. When the target condition is met, the joint multicolor codec is disabled by always encoding the first and second residual blocks separately. When the target condition is not satisfied, if the mode corresponding to the joint multi-color codec is enabled, the joint multi-color codec is enabled by encoding the joint residual block instead of encoding the first residual block and the second residual block separately. color codec. A video bitstream comprising codec data for the joint residual block or separately for the first residual block and the second residual block is then generated.

At the decoder side, a video bitstream comprising encoded data for a multi-color block of a video unit is received, wherein the multi-color block comprises at least a first color block corresponding to a first color component and a color block corresponding to a second color component Second color block. determining whether a target condition is satisfied, wherein the target condition belongs to the group comprising a first condition associated with the number of non-zero quantized coefficients of the joint residual block decoded from the codec material or with the codec unit size of the multi-color block The associated second condition. When the target condition is satisfied, the first residual block of the first color block and the second residual block of the second color block are respectively derived based on codec data. When the target condition is not satisfied, if the mode corresponding to the joint multi-color codec is enabled for the multi-color block, the first residual block and the second residual block are derived from the joint residual block.

In another embodiment, the target condition corresponds to the number of non-zero quantized coefficients being less than a threshold. Thresholds can be predefined or decoded from the video bitstream. The threshold may depend on the CU size associated with the multi-color block.

In yet another embodiment, the first color component corresponds to a luma component and the second color component corresponds to a chroma component, or both the first color component and the second color component correspond to a chroma component.

In yet another embodiment, the set also includes a third condition corresponding to enabling dual luma-chroma trees. In yet another embodiment, the set further includes a fourth condition corresponding to enabling Cross-component Linear Model prediction (Cross-component Linear Model prediction).

In one embodiment, the mode corresponding to the joint multi-color codec has multiple sub-modes. When the target condition is not satisfied, the first sub-mode is based on the distance between the reconstructed multi-color block candidate and the L-shaped adjacent reconstructed pixels. Boundary matching is implicitly determined.

In one embodiment, different numbers of sub-modes of the mode are selected for a Coding Tree Unit (CTU), slice, block or picture according to flags decoded from the video bitstream.

It will be readily appreciated that the components of the present invention as generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations. Accordingly, the following more detailed description of embodiments of the system and method of the present invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention, as shown in the accompanying drawings. Reference in this specification to "an embodiment", "some embodiments" or similar language means that a specific feature, structure or characteristic described in connection with the embodiment can be included in at least one embodiment of the present invention. Thus, appearances of the phrases "in an embodiment" or "in some embodiments" in various places throughout this specification are not necessarily all referring to the same embodiments.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize, however, that the present invention may be practiced without one or more of the specific details, or with other methods, components, etc. In other instances, well-known structures or operations have not been shown or described in detail to avoid obscuring aspects of the invention. The illustrated embodiments of the present invention will be best understood by referring to the drawings, wherein like parts are designated by like numerals throughout. The following description is by way of example only, and simply illustrates some selected embodiments of apparatuses and methods consistent with the invention as claimed herein.

In the video codec process, after prediction, the difference between the predictor and the original samples (residual) is encoded and transmitted to the decoder. The basic process of coding the residual includes transform, quantization, inverse quantization and inverse transform, as described in Figure 1A and Figure 1B.

VVC supports the joint coding of chroma residual (JCCR) tool, in which the chroma residual is jointly coded. It helps to encode chrominance residuals more efficiently because of the high probability of strong correlation between Cb and Cr color components. However, residuals between all color components (including luminance components) usually exhibit some correlation. In order to further improve the encoding and decoding efficiency of JCCR, some improved methods are disclosed below.

Joint codec multicolor component ( Joint Coding Multi-Colour Component , referred to as JCMC )

To exploit the correlation between Y, Cb and Cr residuals, we disclose a method for jointly encoding and decoding Y, Cb and Cr color component residuals. The transformed residual is used to generate the joint codec residual. In the decoder, the residual blocks of Y (resY), Cb (resCb) and Cr (resCr) are derived taking into account the information sent in the bitstream and predetermined rules.

In an embodiment, only one joint residual is encoded and decoded in the decoder. The residual blocks Y, Cb and Cr can be derived by predetermined formulas. For example, the residual block Y is equal to the pixel value of the joint residual, the residual block Cb is equal to half the pixel value of the joint residual, and the residual block Cr is equal to the pixel value of the joint residual multiplied by (-1/2). In another embodiment, only one joint residual is encoded and decoded in the decoder. The residual blocks Y, Cb and Cr can be derived by a predetermined formula indicated by the index (jcmc_mode_idx) sent in the bitstream. Different formulas correspond to different submodes, and the index (jcmc_mode_idx) indicates the specific submode being selected. For example, if jcmc_mode_idx is equal to 1, the residual block Y is equal to the pixel value of the joint residual, the residual block Cb is equal to half the pixel value of the joint residual, and the residual block Cr is equal to the pixel value of the joint residual multiplied by (-1 /2). Otherwise, if jcmc_mode_idx is equal to 2, the residual block Y is equal to the pixel value of the joint residual, the residual block Cb is equal to the pixel value of the joint residual multiplied by (-1/2), and the residual block Cr is equal to the pixel of the joint residual half of the value. For another example, a predetermined formula is used. Parameters used in formulas can be sent in a bitstream. In the formula below, A and B can be represented by the information sent in the bit stream. In another embodiment, the predetermined formula may be any linear operation with or without non-linear operations, such as minimum, maximum or clipping operations. residual block Y = joint residual block Residual block Cb=residual block Y * A Residual block Cr=residual block Y * B

In another embodiment, two joint residuals (joint residual 1 and joint residual 2) are encoded and decoded in the decoder. They are used to derive residual blocks Y, Cb and Cr by predetermined formulas. For example, residual block Y is equal to the average of the pixel values of joint residuals 1 and 2, residual block Cb is equal to half the pixel value of joint residual 1 plus a quarter of the pixel value of joint residual 2, residual block Cr is equal to the sum of the pixel value of joint residual 1 times (-1/2) and the pixel value of joint residual 2 times (-1/4) one quarter. In another embodiment, two joint residuals are encoded and decoded in the decoder. Each sample of the residual block Y, Cb and Cr can be derived by the transformed joint residual. In other words, after the two joint residuals are decoded, one or more transformed joint residuals are derived, and the residual blocks Y, Cb and Cr are generated from the one or more transformed joint residuals. For example, to derive the sample value at position (x, y) of the residual blocks Y, Cb and Cr, the inverse Hadamard transform is applied to the two-dimensional data, the sample value in the joint residual 1 of position (x, y) , the sample value in the joint residual 2 at position (x, y)] generates two transformed joint residual samples [conv-value-1, conv-value-2] at the corresponding position (x, y). Afterwards, the residual blocks Y, Cb and Cr at position (x, y) can be derived. The sample value of residual block Y position (x, y) is equal to conv-value-1, the sample value of residual block Cb position (x, y) is equal to negative conv-value-1 plus conv-value-2, and residual The sample value at position (x, y) of the difference block Cr is equal to conv-value-1 plus negative conv-value-2.

In another embodiment, one or more joint residuals are tested in the encoder and different predetermined derivations are tested. They can be viewed as different prediction modes. In the decoder, a set of syntax sent in the bitstream can be used to indicate which mode and which predetermined derivation formula is used. According to the formula, the residual blocks Y, Cb and Cr can be derived. In another embodiment, according to CU or slice information (such as codec mode), transform type, prediction direction, motion information, intra prediction mode, slice type, etc., the implicit selection can be between different modes or derivation formulas conduct.

In another embodiment, the encoder does not need to send the JCMC sub-pattern (for indicating a predetermined formula) to the decoder; instead, the decoder can use boundary matching to implicitly select a suitable sub-pattern. For example, if there are 3 sub-modes, the decoder can use each sub-mode to derive a luma residual, and add the residual to the predictor to obtain a temporal reconstruction; and the decoder can associate the reconstruction with the L-adjacent (ie, current CU's left/top neighbor reconstructed pixels), compare boundary smoothness and select the best sub-mode (out of 3 sub-modes) with the best boundary smoothness. In other words, boundary smoothness is evaluated for all candidates (ie all sub-patterns), and the candidate that achieves the best boundary smoothness is selected. Boundary smoothness is a measure of smoothness across boundaries. In general, correctly reconstructed blocks are expected to see less discontinuity (i.e. smoother) at the boundaries. In another embodiment, the decoder can choose the best submode by implicitly comparing the temporal reconstruction (i.e., adding the assumed JCMC submode residual to the predictor) with the reference picture (using the current MC) to Computing SAD/SSD, the best JCMC will be implicitly decided as the JCMC with the smallest SAD/SSD.

In another embodiment, for a large CU, the current CU can be divided into multiple sub-TBs instead of one TB for luma, and we can use different JCMC sub-modes for each sub-TB. In another embodiment, different sub-TB JCMC sub-modes can be obtained by comparing the temporal reconstruction of the corresponding sub-TB (i.e., adding the current sub-TB to the corresponding predicted sub-region) with the reference picture (or the boundary smoothness current L adjacent pixels). In this way, there is no need to send syntax for multiple JCMC submodes of different sub-TBs.

In another embodiment, the encoder can decide which modes are to be used for the current CTU/slice/tile/picture and send flags in the CTU/slice/tile/picture. For example, there are 4 predetermined JCMC sub-modes. However, for some CTUs, only 1 sub-mode is useful. Therefore, encoders can send flags to indicate those CTUs that use only 1 JCMC submode. Therefore, for each CU in such a CTU, the JCMC mode flag can be saved since only one sub-mode is available.

In another embodiment, if the number of non-zero residuals in a block is small or the CU size is small, it would be inefficient to send an extra flag for JCMC mode. Therefore, it is recommended to implicitly turn off JCMC mode for high QP, or implicitly turn off intra mode for small CU. When a larger QP value is used, it will result in fewer non-zero residuals. In other words, in one embodiment of the present invention, the JCMC mode is turned off when the number of non-zero coefficients in the residual block is small. Since the decoder can determine whether the number of non-zero coefficients in the residual block is small, the decoder can make the same decision as the encoder without sending a flag. Therefore, JCMC mode can be turned off implicitly, since sending JCMC flags may be detrimental to codec efficiency. In another case, when the CU's current predictor (i.e. no residual is added) pixel is very similar to the top/left neighboring reconstructed pixels, the residual may be small. Since the decoder can also determine in this case whether the current predictor is similar to the top/left neighboring reconstructed pixels, JCMC mode can be implicitly turned off or the number of modes can be implicitly reduced (e.g., implicitly reduce CU by 4 mode to 2 modes) without sending the JCMC flag.

In an embodiment, whether to turn off JCMC mode may be determined by comparing the number of non-zero coefficients in the residual block with a threshold (eg, threshold=3 or 5). If the number of non-zero coefficients in the residual block is less than (or less than or equal to) a threshold, the JCMC mode is switched off (i.e. disabled). Otherwise, JCMC mode is turned on (ie enabled). Thresholds can be predefined or sent in the video bitstream. Also, the threshold can depend on the CU size. For example, the threshold is larger for larger CU sizes.

In another embodiment, when the correlation between the color components is small, the joint coding multi-color components (jointly coding multi-color components, JCMC for short) technology is disabled. For example, JCMC will not be applied when dual trees (eg, luma and chroma codecs with different partition trees) are enabled. For another example, JCMC will not be enabled simultaneously with Low-Frequency Non-Separable Transform (LFNST for short). As we all know, LFNST is another new codec tool included in VVC (JVET-W2002). For another example, JCMC will not be enabled simultaneously with Multiple Transform Selection (MTS for short). As we all know, MTS is another new codec tool included in VVC (JVET-W2002). As another example, JCMC can be enabled together with MTS, but the function of generating the joint codec residual can be different or the same as DCT-2. For another example, for intra-coded blocks, when the intra-frame prediction directions of different color components are different, JCMC is not allowed to be used. In another embodiment, JCMC is applied implicitly when using a Cross-Component Linear Mode (CCLM for short). That is, according to embodiments of the present invention, no additional syntax needs to be sent to the decoder. The use of CCLM mode implies a high correlation between color components. Therefore, if CCLM is implemented, JCMC will always be applied according to one embodiment of the present invention. As we all know, CCLM is another new codec tool included in VVC (JVET-W2002).

For intra prediction, the intra prediction predictors in the lower right region are farther from the L neighbor and are not accurate. Therefore, the lower right part of the CU tends to have larger residual (in the spatial domain) values. If the chroma intra angle is similar to the luma intra angle, the inaccuracy of intra prediction in the lower right region will be consistent between luma intra prediction and chroma intra prediction. Therefore, for intra prediction, the luma residual and chroma residual are more likely to be similar. Therefore, according to one embodiment of the present invention, the luma-to-chroma residual JCMC mode is only enabled for intra mode. In other words, for Inter mode, the luma-to-chroma residual JCMC mode is disabled. In another embodiment, in the intra prediction mode, we can divide the current luma TB and chroma TB into 4 regions (eg, upper left, upper right, lower left, lower right). For the lower right part, we can use JCMC to process as well; for other parts, we can use the regular transformation method. For example, for other parts, we can simply pad the lower right part with 0 to form a filled whole TB, and apply the Y/Cb/Cr normal transformation to the filled whole TB. For the lower right part, we can apply JCMC and send the result. At the decoder side, these 4 parts can be reconstructed accordingly.

In the above disclosure, "enabling" the JCMC mode means that the JCMC mode is enabled, so that the residual block is allowed to use the JCMC mode. Only when JCMC mode is "on", the residual block has the option to use JCMC mode. Whether the residual block uses JCMC is determined by the encoder. If the JCMC mode produces favorable results, the JCMC mode is applied (or enabled) to the residual block. When JCMC mode is turned on, the encoder may decide not to apply (or enable) JCMC on the residual block. In the above disclosure, "off" of the JCMC mode means that the JCMC mode is disabled, so that the residual block is not allowed to use the JCMC mode.

Any of the aforementioned proposed methods can be implemented in the encoder and/or decoder. For example, any of the proposed methods can be implemented in an encoder and/or an inter/intra codec in a decoder. Alternatively, any of the proposed methods can be implemented as an inter/intra encoding/decoding circuit coupled to an encoder and/or a decoder to provide information required for inter/intra encoding and decoding.

FIG. 2 shows a flowchart of an exemplary video decoding system using joint codec of multi-color components according to an embodiment of the present invention. The steps shown in the flowchart can be implemented as program code executable on one or more processors (eg, one or more CPUs) at the encoder side. The steps shown in the flowcharts may also be implemented based on hardware, such as one or more electronic devices or processors arranged to perform the steps in the flowcharts. According to the method, in step 210 a video bitstream is received, the video bitstream comprising codec data for a multi-color block of a video unit, wherein the multi-color block comprises at least a first color component corresponding to a first color component A color block and a second color block corresponding to the second color component. In step 220, it is determined whether a target condition is satisfied, wherein the target condition belongs to the group comprising the first condition associated with the number of non-zero quantized coefficients of the joint residual block decoded from the codec material or with the multi-color block The second condition associated with the codec unit size. When the target condition is met, step 230 is performed. Otherwise, step 240 is executed. In step 230, the first residual block of the first color block and the second residual block of the second color block are respectively derived based on codec data. In step 240, if the mode corresponding to the joint multi-color codec is enabled for the multi-color block, both the first residual block and the second residual block are derived from the joint residual block.

FIG. 3 shows a flowchart of an exemplary video coding system utilizing joint coding and decoding of multi-color components according to an embodiment of the present invention. According to the method, at step 310, input data comprising a multi-color patch of a video unit is received, wherein the multi-color patch includes at least a first color patch corresponding to a first color component and a second color corresponding to a second color component piece. In step 320, the first residual block of the first color block is determined by using the first predictor. In step 330, a second residual block of the second color block is determined by using the second predictor. In step 340, it is determined whether a target condition is satisfied, wherein the target condition belongs to the group comprising the first condition associated with the number of non-zero quantized coefficients of the joint residual block or with the codec unit size of the multi-color block The second condition of joint, and wherein the joint residual block is generated based on the first residual block and the second residual block. When the target condition is met, step 350 is performed. Otherwise, step 360 is executed. In step 350, the joint multicolor codec is disabled by encoding the first residual block and the second residual block separately. In step 360, if the mode corresponding to the joint multicolor codec is enabled for the multicolor block, the joint multicolor codec encodes the joint residual block instead of separately encoding the first residual block and the second residual block. Residual block to enable. In step 370, a video bitstream is generated, the video bitstream including codec data for the joint residual block or for the first residual block and the second residual block respectively.

The shown flowchart is intended to illustrate an example of video codec according to the present invention. Those skilled in the art may modify each step, rearrange steps, split steps or combine steps to implement the present invention without departing from the spirit of the present invention. In this disclosure, specific syntax and semantics are used to illustrate examples to implement the embodiments of the invention. A skilled artisan can implement the present invention by substituting equivalent syntax and semantics for the above syntax and semantics without departing from the spirit of the present invention.

The foregoing description is presented to enable one of ordinary skill in the art to practice the invention presented in the context of a particular application and its requirements. Various modifications to the described embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments. Thus, the present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. In the above detailed description, various specific details have been set forth in order to provide a thorough understanding of the present invention. However, those skilled in the art will understand that the present invention can be practiced.

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

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described examples are to be considered in all respects only as illustrative and not restrictive. Accordingly, the scope of the invention is indicated by the appended claims rather than by the foregoing description. All changes within the equivalent meaning and range of the claimed patent scope shall be included in its scope.

110:Intra prediction 112: Inter prediction 114: switch 116: Adder 118:Transformation 120: quantization 122: Entropy Encoder 124: Inverse quantization 126: Inverse transformation 128:REC 130: loop filter 134: Reference picture buffer 136: Forecast data 140:Entropy decoder 150:Intra prediction 152:MC 210, 220, 230, 240, 310, 320, 330, 330, 340, 350, 360: steps

FIG. 1A shows an example adaptive inter/intra video codec system incorporating loop processing. Figure 1B shows the corresponding decoder of the encoder in Figure 1A. FIG. 2 shows a flow chart of an exemplary video decoding system utilizing joint coding and decoding of multi-color components according to an embodiment of the present invention. FIG. 3 shows a flowchart of an exemplary video coding system utilizing joint coding and decoding of multi-color components according to an embodiment of the present invention.

210, 220, 230, 240: steps

Claims (21)

A video decoding method, the method comprising: receiving a video bitstream including codec data for a multi-color codec block of a video unit, wherein the multi-color codec block includes at least a first color block corresponding to a first color component and corresponding to a second color block of a second color component; determining whether a target condition is satisfied, wherein the target condition belongs to a group comprising a first value associated with a number of non-zero quantized coefficients of a joint codec residual block decoded from the codec material. condition or a second condition associated with a codec unit size of the multicolor codec block; If the target condition is met: deriving a first residual block of the first color block and a second residual block of the second color block respectively based on the codec data; and otherwise: If a mode corresponding to the joint multicolor codec is enabled for the multicolor codec block, a first residual block and a second residual block are derived from the joint codec residual block. The video decoding method as claimed in claim 1, wherein the target condition corresponds to the number of the non-zero quantized coefficients being less than a threshold. The video decoding method as claimed in claim 2, wherein the threshold is predefined or decoded from the video bit stream. The video decoding method as claimed in claim 2, wherein the threshold depends on a codec unit size associated with the multi-color codec block. The video decoding method according to Claim 1, wherein the first color component corresponds to a luminance component, the second color component corresponds to a chrominance component, or the first color component and the second color component correspond to multiple color components. The video decoding method as claimed in claim 1, wherein the group further includes a third condition corresponding to enabling a plurality of dual luma-chrominance trees. The video decoding method according to claim 1, wherein the group further includes a fourth condition corresponding to enabling cross-component linear model prediction. The video decoding method as described in Claim 1, wherein the mode corresponding to the joint multi-color codec has multiple sub-modes, and when the target condition is not satisfied, a first sub-mode is based on the reconstructed joint multi-color code Boundary matching between multiple candidates of the decoded block and multiple L-shaped adjacent reconstructed pixel boundaries is determined implicitly. The video decoding method as claimed in claim 1, wherein a plurality of different numbers of subcodes of the mode are selected for a plurality of codec tree units, slices, tiles or pictures according to a plurality of flags decoded from the video bit stream model. A video decoding device comprising one or more electronic circuits or processors for: receiving a video bitstream including codec data for a multi-color codec block of a video unit, wherein the multi-color codec block includes at least a first color block corresponding to a first color component and corresponding to a second color block of a second color component; determining whether a target condition is satisfied, wherein the target condition belongs to a group comprising a first value associated with a number of non-zero quantized coefficients of a joint codec residual block decoded from the codec material. condition or a second condition associated with a codec unit size of the multicolor codec block; If the target condition is met: deriving a first residual block of the first color block and a second residual block of the second color block respectively based on the codec data; and otherwise: If a mode corresponding to the joint multicolor codec is enabled for the multicolor codec block, a first residual block and a second residual block are derived from the joint codec residual block. A video encoding method, the method comprising: receiving input data including a multi-color codec block of a video unit, wherein the multi-color codec block includes at least a first color block corresponding to a first color component and a second color block corresponding to a second color component color blocks; determining a first residual block of the first color block by using a first predictor; determining a second residual block of the second color block by using a second predictor; determining whether a target condition is satisfied, wherein the target condition belongs to a group comprising a first condition associated with a number of non-zero quantized coefficients of a jointly coded residual block or associated with the multi-color codec residual block. decoding a second condition associated with a codec unit size of the block, wherein the joint codec residual block is generated based on the first residual block and the second residual block; If the target condition is met: disabling joint multicolor codecs by encoding the first residual block and the second residual block separately; otherwise: If a mode corresponding to the joint multicolor codec is enabled for the multicolor codec block, by encoding the joint codec residual block instead of separately encoding the first residual block and the second residual block to enable the joint multicolor codec; and A video bit stream is generated, the video bit stream includes codec data for the joint codec residual block or respectively for the first residual block and the second residual block. The video coding method as claimed in claim 11, wherein the target condition corresponds to the number of the non-zero quantized coefficients being less than a threshold. The video encoding method according to claim 12, wherein the threshold is predefined or encoded in the video bit stream. The video coding method as claimed in claim 12, wherein the threshold depends on a codec unit size associated with the multi-color codec block. The video encoding method as described in Claim 11, wherein the first color component corresponds to a luminance component, the second color component corresponds to a chrominance component, or the first color component and the second color component correspond to multiple color components. The video coding method as claimed in claim 11, wherein the group further includes a third condition corresponding to enabling a plurality of dual luma-chroma trees. The video coding method as claimed in claim 11, wherein the group further includes a fourth condition corresponding to enabling cross-component linear model prediction. The video coding method as described in claim 11, wherein the mode corresponding to the joint multi-color codec has multiple sub-modes, and when the target condition is not satisfied, a first sub-mode is based on the reconstructed joint multi-color code Boundary matching between multiple candidates of the decoded block and multiple L-shaped adjacent reconstructed pixel boundaries is determined implicitly. The video coding method as claimed in claim 11, wherein a plurality of different numbers of sub-modes are selected for a plurality of codec tree units, slices, tiles or pictures. The video encoding method of claim 19, wherein the different numbers of sub-modes for the codec tree units, slices, tiles or pictures are encoded in the video bitstream. A video encoding device comprising one or more electronic circuits or processors for: receiving input data including a multi-color codec block of a video unit, wherein the multi-color codec block includes at least a first color block corresponding to a first color component and a second color block corresponding to a second color component color blocks; determining a first residual block of the first color block by using a first predictor; determining a second residual block of the second color block by using a second predictor; determining whether a target condition is satisfied, wherein the target condition belongs to a group comprising a first condition associated with a number of non-zero quantized coefficients of a jointly coded residual block or associated with the multi-color codec residual block. decoding a second condition associated with a codec unit size of the block, wherein the joint codec residual block is generated based on the first residual block and the second residual block; If the target condition is met: disabling joint multicolor codecs by encoding the first residual block and the second residual block separately; otherwise: If a mode corresponding to the joint multicolor codec is enabled for the multicolor codec block, by encoding the joint codec residual block instead of separately encoding the first residual block and the second residual block to enable the joint multicolor codec; and A video bit stream is generated, the video bit stream includes codec data for the joint codec residual block or respectively for the first residual block and the second residual block.

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