General constraint information for video encoding and decoding

Abstract

Methods for implementing Adaptive Color Transformation (ACT) during image / video encoding and decoding are described. Example methods for video processing include, for a conversion between a video comprising blocks and a video bitstream, determining that the block size is greater than the maximum allowed size of the ACT mode, and performing the conversion based on this determination, wherein, in response to the block size being greater than the maximum allowed size of the ACT mode, the block is divided into multiple sub-blocks, and wherein each of the multiple sub-blocks shares the same prediction mode, and the ACT mode is enabled at the sub-block level.

Description

[0001] Cross-reference of related applications

[0002] This application is a Chinese national phase application filed on January 5, 2021, with international patent application number PCT / CN2021 / 070279, claiming priority to international patent application number PCT / CN2020 / 070368 filed on January 5, 2020. The entire disclosure of the above applications is incorporated herein by reference and forms part of this disclosure. Technical Field

[0003] This patent document relates to image encoding and decoding as well as video encoding and decoding. Background Technology

[0004] Digital video accounts for the largest share of bandwidth usage on the internet and other digital communication networks. As the number of connected user devices capable of receiving and displaying video increases, the bandwidth demand for digital video is expected to continue to grow. Summary of the Invention

[0005] This document discloses systems, methods, and apparatuses for video encoding and decoding, which, in addition to using other encoding and decoding tools, employ the Adaptive Color Transformation (ACT) mode.

[0006] In one example aspect, a video processing method is disclosed. The method includes, for a conversion between a current video block and a bitstream of the video, determining a maximum and / or minimum permissible size of an adaptive color transformation (ACT) mode used for encoding and decoding the current video block; and performing the conversion based on the determination.

[0007] In another example aspect, a video processing method is disclosed. The method includes, for a conversion between a current video block and a bitstream of the video, determining a maximum allowed palette size and / or a minimum allowed prediction size for a palette mode used to encode and decode the current video block; and performing the conversion based on the determination, wherein the maximum allowed palette size and / or minimum allowed prediction size are based on the encoding and decoding characteristics of the current video block.

[0008] In yet another example aspect, a video processing method is disclosed. The method includes performing a conversion between a current video block and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the current video block is encoded and decoded using a palette-mode codec tool, and wherein the format rule specifies that parameters associated with the binarization of the escaped symbols of the current video block in the bitstream are based on the encoding and decoding information of the current video block.

[0009] In yet another example aspect, a video processing method is disclosed. The method includes, for a conversion between a video comprising blocks and a bitstream of the video, determining that the size of the blocks is greater than the maximum permissible size of an Adaptive Color Transformation (ACT) mode; and performing a conversion based on the determination, wherein, in response to the block size being greater than the maximum permissible size of the ACT mode, the blocks are divided into multiple sub-blocks, and wherein each sub-block in the multiple sub-blocks shares the same prediction mode, and the ACT mode is enabled at the sub-block level.

[0010] In yet another example aspect, a video processing method is disclosed. The method includes performing a conversion between a current video block and a bitstream of the video, wherein the bitstream conforms to a format rule specifying whether signaling in the bitstream indicates the use of an Adaptive Color Transformation (ACT) mode on the current video block, based on at least one of the dimensions of the current video block or the maximum permissible size of the ACT mode.

[0011] In yet another example aspect, a video processing method is disclosed. The method includes performing a conversion between a current video unit and a bitstream of video, wherein the bitstream conforms to a format rule specifying whether a first flag is included in the bitstream, and wherein the first flag indicates whether a second flag in a sequence parameter set (SPS) specifies that the adaptive color transformation (ACT) mode of the current video unit is disabled.

[0012] In yet another example aspect, a video processing method is disclosed. The method includes performing a conversion between a current video unit of a video and a bitstream of the video, wherein the bitstream conforms to a format rule specifying whether a first flag is included in the bitstream, and wherein the first flag indicates whether a second flag in a sequence parameter set (SPS) specifies whether a block-based incremental pulse codec modulation (BDPCM) mode for the current video unit is disabled.

[0013] In yet another example aspect, a video processing method is disclosed. The method includes performing a conversion between a current video unit of a video and a bitstream of the video, wherein the bitstream conforms to a format rule specifying whether a first flag is included in the bitstream, and wherein the first flag indicates whether a second flag in a sequence parameter set (SPS) specifies a block-based incremental pulse codec modulation (BDPCM) mode that disables the chroma component of the current video unit.

[0014] In yet another example aspect, a video processing method is disclosed. The method includes performing a conversion between a current video unit and a bitstream of video, wherein the bitstream conforms to a format rule specifying whether a first flag is included in the bitstream, and wherein the first flag indicates whether a second flag in a sequence parameter set (SPS) specifies that the palette of the current video unit is disabled.

[0015] In yet another example aspect, a video processing method is disclosed. The method includes performing a conversion between a current video unit of video and a bitstream of video, wherein the bitstream conforms to a format rule specifying whether a first flag is included in the bitstream, and wherein the first flag indicates whether a second flag in a sequence parameter set (SPS) specifies that a reference picture resampling (RPR) mode for the current video unit is disabled.

[0016] In yet another example aspect, a video processing method is disclosed. This method includes performing a conversion between a current video block and the video bitstream according to a rule that specifies the application of an additional quantization parameter offset when the Adaptive Color Transform (ACT) mode is enabled for the current video block.

[0017] In yet another example aspect, a video processing method is disclosed. This method includes performing a conversion between a current video block and a bitstream representation of the video according to rules, wherein the current video block is encoded and decoded using a joint CbCr encoding / decoding mode, wherein a YCgCo color transform or an inverse YCgCo color transform is applied to the current video block, and wherein the rules specify that: since the current video block is encoded and decoded using the joint CbCr encoding / decoding mode in which the YCgCo color transform is used, a quantization parameter offset value different from -5 is used in the picture header (PH) or picture parameter set (PPS) associated with the current video block.

[0018] In yet another example aspect, a video processing method is disclosed. This method includes performing a conversion between a current video block and a bitstream representation of the video according to rules, wherein the current video block is encoded and decoded using a joint CbCr encoding / decoding mode, wherein a YCgCo-R color transform or an inverse YCgCo-R color transform is applied to the current video block, and wherein the rules specify that: since the current video block is encoded and decoded using the joint CbCr encoding / decoding mode in which the YCgCo-R color transform is used, a quantization parameter offset value different from a predetermined offset is used in the picture header (PH) or picture parameter set (PPS) associated with the current video block.

[0019] In yet another example aspect, a video encoder apparatus is disclosed. The video encoder includes a processor configured to implement the methods described above.

[0020] In yet another example aspect, a video decoder apparatus is disclosed. The video decoder includes a processor configured to implement the methods described above.

[0021] In yet another example aspect, a non-transitory computer-readable medium on which code is stored is disclosed. This code embodies one of the methods described herein in the form of processor-executable code.

[0022] This document describes these and other features. Attached Figure Description

[0023] Figure 1 The flow of the screen content codec (SCC) decoder for Loop Adaptive Color Transformation (ACT) is shown.

[0024] Figure 2 The decoding process using ACT is shown.

[0025] Figure 3 An example of a block encoded and decoded in palette mode is shown.

[0026] Figure 4 An example of using palette prediction signaling to notify palette entries is shown.

[0027] Figure 5 Examples of horizontal and vertical traversal scans are shown.

[0028] Figure 6 This shows an example of encoding and decoding a palette index.

[0029] Figure 7 This is a block diagram illustrating an example video processing system according to various embodiments of the present disclosure.

[0030] Figure 8 This is a block diagram of an example hardware platform used for video processing.

[0031] Figure 9 This is a block diagram illustrating a video encoding / decoding system according to various embodiments of the present disclosure.

[0032] Figure 10 This is a block diagram illustrating an encoder according to various embodiments of the present disclosure.

[0033] Figure 11 This is a block diagram illustrating a decoder according to various embodiments of the present disclosure.

[0034] Figure 12-24 A flowchart of an example method for video processing is shown. Detailed Implementation

[0035] The use of chapter headings in this document is for ease of understanding and does not imply that the technologies and embodiments disclosed in each chapter are applicable only to that chapter. Furthermore, the use of H.266 terminology in some descriptions is merely for ease of understanding and not intended to limit the scope of the disclosed technologies. Therefore, the technologies described herein are also applicable to other video codec protocols and designs.

[0036] 1. Summary

[0037] This patent document relates to image / video codec technology. Specifically, it concerns adaptive color transformation in image / video codecs. It can be applied to standards under development, such as general video codecs. It can also be applied to future video codec standards or video codecs.

[0038] 2. Brief explanation

[0039] Video codec standards have primarily evolved through the development of standards by the renowned International Telecommunication Union (ITU) Telecommunication Standardization Sector (ITU-T) and the International Organization for Standardization (ISO) / International Electrotechnical Commission (IEC). ITU-T produced H.261 and H.263, ISO / IEC produced MPEG-1 and MPEG-4 Visual, and the two organizations jointly produced H.262 / MPEG-2 Video and H.264 / MPEG-4 Advanced Video Codec (AVC), as well as the H.265 / HEVC standard. Since H.262, video codec standards have been based on a hybrid video codec architecture, using temporal prediction plus transform coding. To explore future video codec technologies beyond HEVC, the Video Codec Experts Group (VCEG) and the Moving Picture Experts Group (MPEG) jointly established the Joint Video Exploration Team (JVET) in 2015. Since then, JVET has adopted many new methods and applied them to reference software called the Joint Exploration Model (JEM). In April 2018, the Joint Video Experts Group (JVET) was established between VCEG (Q6 / 16) and ISO / IEC JTC1 SC29 / WG11 (MPEG) to work on a VVC standard that aims to reduce the bit rate by 50% compared to HEVC.

[0040] The latest version of the VVC draft, namely Universal Video Codec (Draft 7), can be found at: http: / / phenix.it-sudparis.eu / jvet / doc_end_user / documents / 16_Geneva / wg11 / JVET-P2001-v14.zip

[0041] The latest reference software for VVC, VTM, can be found at: https: / / vcgit.hhi.fraunhofer.de / jvet / VVCSoftware_VTM / tags / VTM-7.0

[0042] 2.1. Adaptive Color Transformation (ACT) in HEVC-SCC

[0043] At the 18th JCT-VC conference (June 30 – July 9, 2014, Sapporo, Japan), Adaptive Color Transform (ACT) was adopted in HEVC Screen Content Codec (SCC) test model 2. ACT performs loop color space conversion in the prediction residual domain using a color transformation matrix based on the YCoCg and YCoCg-R color spaces. ACT is adaptively enabled or disabled at the CU level using the flag cu_residual_act_flag. ACT can be combined with Cross Component Prediction (CCP), another inter-frame component decorrelation method already supported in HEVC. When both are enabled, ACT is performed after CCP at the decoder, as shown below. Figure 1 The system 100 is shown.

[0044] 2.1.1. Color Space Conversion in ACT

[0045] Color space conversion in ACT is based on the YCoCg-R transform. Both lossy and lossless encoding / decoding (cu_transquant_bypass_flag = 0 or 1) use the same inverse transform, but in the case of lossy encoding / decoding, an additional 1-bit left shift is applied to the Co and Cg components. Specifically, the following color space transformations are used for forward and backward conversions in both lossy and lossless encoding / decoding:

[0046] Forward transform of lossy encoding / decoding (non-standard):

[0047]

[0048] Forward transform of lossless encoding and decoding (non-standard):

[0049] Co = RB

[0050] t = B + (Co >> 1)

[0051] Cg=(Gt)

[0052] Y = t + (Cg >> 1)

[0053] Backward transformation (standard):

[0054] if(lossy){

[0055] Co = Co << 1

[0056] Cg = Cg << 1

[0057] }

[0058] t = Y - (Cg >> 1)

[0059] G = Cg + t

[0060] B = t - (Co >> 1)

[0061] R = Co + b

[0062] The forward color transform is not normalized, where its norm is approximately equal to Y and Cg. And for Co, it is approximately equal to To compensate for the non-normalized nature of the forward transform, incremental QPs of (-5, -3, -5) are applied to (Y, Co, Cg) respectively. In other words, for a given "normal" QP of the CU, if ACT is enabled, the quantization parameters are set to equal to (QP-5, QP-3, QP-5) for (Y, Co, Cg). The adjusted quantization parameters only affect the quantization and inverse quantization of the residuals in the CU. For deblocking, the "normal" QP values ​​are still used. Clipping to 0 is applied to the adjusted QP values ​​to ensure they do not become negative. Note that this QP adjustment only applies to lossy codecs, as quantization is not performed in lossless codecs (cu_transquant_bypass_flag = 1). In SCM 4, PPS / strip-level signaling with additional QP offset values ​​was introduced. These QP offset values, instead of (-5, -3, -5), can be used for the CU when applying adaptive color transform.

[0063] When the input bit depths of the color components are different, an appropriate left shift is applied during ACT to align the sample bit depth with the maximum bit depth, and an appropriate right shift is applied after ACT to restore the original sample bit depth.

[0064] 2.2. ACT in VVC

[0065] Figure 2 A flowchart 200 depicts the application of VVC in ACT. (e.g., ...) Figure 2 As shown, color space conversion is performed in the residual domain. Specifically, an additional decoding module, the inverse ACT, is introduced after the inverse transform to convert the residual from the YCgCo domain back to the original domain.

[0066] In VVC, a CU leaf node is also used as a unit for transform processing unless the maximum transform size is less than the width or height of a codec unit (CU). Therefore, in the proposed implementation, an ACT flag is signaled for a CU to select a color space for encoding and decoding its residuals. Furthermore, following the HEVC ACT design, for inter-frame CUs and intra-frame block copy (IBC) CUs, ACT is enabled only if there is at least one non-zero coefficient in the CU. For intra-frame CUs, ACT is enabled only if the chroma component selects the same intra-prediction mode as the luma component, i.e., derivation mode (DM).

[0067] The core transform used for color space conversion is consistent with the core transform used for HEVC. Additionally, similar to the ACT design in HEVC, a QP adjustment of (-5, -5, -3) is applied to the transform residual to compensate for changes in the dynamic range of the residual signal before and after the color transformation.

[0068] On the other hand, both forward and inverse color transformations require access to the residuals of all three components. Correspondingly, in the proposed implementation, ACT is disabled in two cases where not all residuals of the three components are available.

[0069] 1. Split Tree Partitioning: When applying split tree, the luma and chroma samples within a codec tree unit (CTU) are partitioned according to different structures. This results in the CU in the luma tree containing only the luma component, while the CU in the chroma tree contains only the two chroma components.

[0070] 2. Intra-Frame Sub-Partition Prediction (ISP): ISP sub-partitions are applied only to luma, while chroma signals are encoded and decoded without partitioning. In current ISP designs, except for the final ISP sub-partition, other sub-partitions contain only the luma component.

[0071] The text of the codec unit in the VVC draft is shown below.

[0072]

[0073]

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080] A value of 1 for `cu_act_enabled_flag` indicates that the residual of the current codec unit is encoded and decoded in the YCgCo color space. A value of 0 for `cu_act_enabled_flag` indicates that the residual of the current codec unit is encoded and decoded in the original color space. If `cu_act_enabled_flag` does not exist, it is inferred to be equal to 0.

[0081] 2.3. Transform Skip Mode in VVC

[0082] In HEVC, for example, a transform skip mode can be used to encode and decode the block residuals, which completely skips the block's transform process. Furthermore, for transform skip blocks, the minimum allowed quantization parameter (QP) notified by the signaling in SPS is used, which is set to 6 * (internalBitDepth – inputBitDepth) + 4 in VTM 7.0.

[0083] 2.4. Block-based Incremental Pulse Codec Modulation (BDPCM)

[0084] In JVET-M0413, a block-based incremental pulse coding-decoding modulation (BDPCM) is proposed to efficiently encode and decode screen content, which is then applied to VVC.

[0085] The prediction direction used in BDPCM can be either vertical or horizontal prediction mode. Intra-prediction is performed on the entire block by copying samples in a prediction direction (horizontal or vertical) similar to intra-prediction. The residual is quantized, and the increment between the quantized residual and its predicted (horizontal or vertical) quantized value is encoded and decoded. This can be described as follows: For a block of size M (rows) × N (columns), after performing intra-prediction horizontally (copying left neighbor pixel values ​​across the prediction block row by row) or vertically (copying the top neighbor row to each row in the prediction block) using unfiltered samples from the upper or left block boundary, let r i,j Let , 0≤i≤M-1, 0≤j≤N-1 be the prediction residuals. Let Q(r) i,j ), 0≤i≤M-1, 0≤j≤N-1 represent residuals r i,j The quantized version is then used, where the residual is the difference between the original block and the predicted block values. The block DPCM is then applied to the quantized residual samples to obtain an element-wise... Modified M×N array When signaling notifies the vertical BDPCM:

[0086]

[0087] For horizontal forecasting, similar rules apply, and residual quantization samples are obtained as follows:

[0088]

[0089] Residual Quantization Samples It is sent to the decoder.

[0090] On the decoder side, the above calculation is inverted to produce Q(r). i,j ), 0≤i≤M-1, 0≤j≤N-1.

[0091] For vertical prediction cases

[0092]

[0093] Regarding the horizontal situation

[0094]

[0095] Inverse quantization residual Q -1 (Q(r i,j Added to the intra-block prediction values ​​to produce reconstructed sample values.

[0096] The main advantage of this approach is that inverse BDPCM can be performed dynamically during coefficient resolution, simply by adding the predicted values ​​as coefficients, or it can be performed after resolution.

[0097] In VTM 7.0, BDPCM can also be applied to chroma blocks, and chroma BDPCM has a separate flag and BDPCM direction that are different from the luminance BDPCM mode.

[0098] 2.5. Scaling process of transformation coefficients

[0099] The text related to the scaling process of the transform coefficients in JVET-P2001-vE is given as follows.

[0100] The input for this process is:

[0101] – Specifies the brightness position (xTbY, yTbY) of the current brightness transformation block relative to the top-left brightness sample of the current image.

[0102] – The variable nTbW specifies the width of the transform block.

[0103] – The variable nTbH specifies the height of the transform block.

[0104] – The variable predMode specifies the prediction mode of the encoding / decoding unit.

[0105] – The variable cIdx specifies the color components of the current block.

[0106] The output of this process is an array d of (nTbW)×(nTbH) with scaling transformation coefficients of elements d[x][y].

[0107] The quantization parameter qP is derived as follows:

[0108] – If cIdx equals 0, the following applies:

[0109] qP=QP'Y (1129)

[0110] Otherwise, if TuCResMode[xTbY][yTbY] equals 2, then the following applies:

[0111] qP=QP'CbCr (1130)

[0112] Otherwise, if cIdx equals 1, the following applies:

[0113] qP=QP'Cb (1131)

[0114] Otherwise (cIdx equals 2), the following applies:

[0115] qP=QP'Cr (1132)

[0116] Modify the quantization parameter qP, and derive the variables rectNonTsFlag and bdShift as follows:

[0117] – If transform_skip_flag[xTbY][yTbY][cIdx] equals 0, then the following applies:

[0118] qP=qP-(cu_act_enabled_flag[xTbY][yTbY]?5:0) (1133)

[0119] rectNonTsFlag=(((Log2(nTbW)+Log2(nTbH))&1)==1)? 1:0 (1134)

[0120] bdShift=BitDepth+rectNonTsFlag+ (1135)

[0121] ((Log2(nTbW)+Log2(nTbH)) / 2)-5+pic_dep_quant_enabled_flag

[0122] – Otherwise (transform_skip_flag[xTbY][yTbY][cIdx] equals 1), the following applies:

[0123] qP=Max(QpPrimeTsMin,qP)-(cu_act_enabled_flag[xTbY][yTbY]?5:0)(1136)

[0124] rectNonTsFlag = 0 (1137)

[0125] bdShift = 10 (1138)

[0126] The variable bdOffset is derived as follows:

[0127] bdOffset = (1 <<bdShift)> >1 (1139)

[0128] The list levelScale[][] is defined as levelScale[j][k] = {{40,45,51,57,64,72},{57,64,72,80,90,102}}, where j = 0..1, k = 0..5.

[0129] The (nTbW)×(nTbH) array dz is set to be equal to the (nTbW)×(nTbH) array TransCoeffLevel[xTbY][yTbY][cIdx].

[0130] The following applies to the derivation of the scaling transformation coefficients d[x][y] (where x = 0..nTbW-1, y = 0..nTbH-1):

[0131] – Derive the intermediate scaling factor m[x][y] as follows:

[0132] – m[x][y] is set to 16 if one or more of the following conditions are true:

[0133] –sps_scaling_list_enabled_flag equals 0.

[0134] –pic_scaling_list_present_flag equals 0.

[0135] –transform_skip_flag[xTbY][yTbY][cIdx] equals 1.

[0136] –scaling_matrix_for_lfnst_disabled_flag equals 1, and lfnst_idx[xTbY][yTbY] is not equal to 0.

[0137] –Otherwise, the following applies:

[0138] – Derive the variable id based on predMode, cIdx, nTbW, and nTbH as specified in Table 36, and derive the variable log2MatrixSize as follows:

[0139] log2MatrixSize=(id<2)? 1: (id<8)? 2:3(1140)

[0140] – The scaling factor m[x][y] is derived as follows:

[0141] m[x][y]=ScalingMatrixRec[id][i][j]

[0142] Where i = (x <<log2MatrixSize)> Log2(nTbW),

[0143] j = (y <<log2MatrixSize)> Log2(nTbH)(1141)

[0144] – If id is greater than 13 and x and y are both equal to 0, then m[0][0] is further modified as follows:

[0145] m[0][0]=ScalingMatrixDCRec[id-14](1142)

[0146] Note – The quantization matrix element m[x][y] can be zeroed out when any of the following conditions are true.

[0147] -x is greater than 32

[0148] -y is greater than 32

[0149] - The decoded tu is not encoded or decoded using the default transform mode (i.e., transform type is not equal to 0) and x is greater than 16.

[0150] - The decoded tu is not encoded or decoded using the default transform mode (i.e., the transform type is not equal to 0), and y is greater than 16.

[0151] – Derive the scaling factor ls[x][y] as follows:

[0152] – If pic_dep_quant_enabled_flag equals 1 and transform_skip_flag[xTbY][yTbY][cIdx] equals 0, then the following applies:

[0153] ls[x][y]=(m[x][y]*levelScale[rectNonTsFlag][(qP+1)%6])<<((qP+1)

[0154] / 6)(1143)

[0155] – Otherwise (pic_dep_quant_enabled_flag equals 0 or transform_skip_flag[xTbY][yTbY][cIdx] equals 1), the following applies:

[0156] ls[x][y]=(m[x][y]*levelScale[rectNonTsFlag][qP%6])<<(qP / 6)(1144)

[0157] – When BdpcmFlag[xTbY][yYbY][cIdx] equals 1, modify dz[x][y] as follows:

[0158] – If BdpcmDir[xTbY][yYbY][cIdx] equals 0 and x is greater than 0, then the following content...

[0159] Applicable to:

[0160] dz[x][y]=Clip3(CoeffMin,CoeffMax,dz[x-1][y]+dz[x][y])(1145)

[0161] Otherwise, if BdpcmDir[xTbY][yTbY][cIdx] equals 1 and y is greater than 0, then...

[0162] The following content applies:

[0163] dz[x][y]=Clip3(CoeffMin,CoeffMax,dz[x][y-1]+dz[x][y])(1146)

[0164] – Derive the value dnc[x][y] as follows:

[0165] dnc[x][y]=(dz[x][y]*ls[x][y]+bdOffset)>>bdShift(1147)

[0166] – The scaling transformation coefficients d[x][y] are derived as follows:

[0167] d[x][y]=Clip3(CoeffMin,CoeffMax,dnc[x][y])(1148)

[0168] Table 36 - Specifications for the scaling matrix identifier variable id based on predMode, cIdx, nTbW, and nTbH

[0169]

[0170] 2.6. Palette Mode

[0171] 2.6.1. The concept of palette mode

[0172] The basic idea behind palette mode is that pixels in a CU are represented by a small set of representative color values. This set is called the palette. Samples outside the palette can also be indicated by signaling an escape symbol after the (potentially quantized) component values. Such pixels are called escape pixels. Palette mode is as follows: Figure 3 As shown. Figure 3 As shown, for each pixel with three color components (luminance and two chrominance components), an index of the color palette is established, and the block can be reconstructed based on the established values ​​in the color palette.

[0173] 2.6.2. Encoding and Decoding Palette Entries

[0174] For encoding and decoding of palette entries, palette prediction values ​​are preserved. The maximum size of the palette and the palette prediction values ​​are signaled in the SPS. In HEVC-SCC, the `palette_predictor_initializer_present_flag` is introduced in the PPS. When this flag is 1, the entry used to initialize the palette prediction values ​​is signaled in the bitstream. Palette prediction values ​​are initialized at the beginning of each CTU line, each stripe, and each slice. Depending on the value of `palette_predictor_initializer_present_flag`, the palette prediction values ​​are either reset to 0 or initialized using the palette prediction value initializer entry signaled in the PPS. In HEVC-SCC, a palette prediction value initializer of size 0 is enabled to allow explicit disabling of palette prediction value initialization at the PPS level.

[0175] For each entry in the palette prediction, a signal is sent to a reuse flag to indicate whether it is part of the current palette. This is in Figure 4As shown in the diagram, a reuse flag is sent using zero-run-length encoding / decoding. Following this, the number of new palette entries is notified using 0th-order exponent Golomb (EG) code (i.e., EG-0) signaling. Finally, the component values ​​of the new palette entries are notified via signaling.

[0176] 2.6.3. Encoding and Decoding of Palette Index

[0177] use Figure 5 The horizontal and vertical traversal scans shown encode and decode the palette index. The scan order is explicitly signaled in the bitstream using the `palette_transpose_flag`. For the remainder of the subsection, it is assumed that the scan is horizontal.

[0178] Two palette example modes are used to encode and decode the palette index: "COPY_LEFT" and "COPY_ABOVE". In "COPY_LEFT" mode, the palette index is assigned to the decoding index. In "COPY_ABOVE" mode, the palette index of the sample in the row above is copied. For both "COPY_LEFT" and "COPY_ABOVE" modes, a run-length value is signaled, specifying the number of subsequent samples that are also encoded and decoded using the same mode.

[0179] In palette mode, the index value of an escape symbol is the number of palette entries. Furthermore, when an escape symbol is part of a run in "COPY_LEFT" or "COPY_ABOVE" mode, an escape component value is signaled for each escape symbol. The encoding and decoding of the palette index is as follows: Figure 6 As shown.

[0180] This syntax is performed as follows: First, signaling informs the number of index values ​​for the CU. Then, truncated binary codec signaling informs the actual index values ​​for the entire CU. Both the index number and the index values ​​are encoded / decoded in bypass mode. This groups the bypass bits associated with the indexes together. Then, interleaved signaling informs the palette sampling mode (if necessary) and run length. Finally, the component escape values ​​corresponding to the escape symbols of the entire CU are grouped together and encoded / decoded in bypass mode. The binarization of the escape symbols is EG of the third-order codec, i.e., EG-3.

[0181] The signaling notification appends the `last_run_type_flag` syntax element after the index value. This syntax element, combined with the number of indices, eliminates the need for the signaling notification to correspond to the run value of the last run in the block.

[0182] In HEVC-SCC, a palette mode is also enabled for 4:2:2, 4:2:0, and monochrome chroma formats. For all chroma formats, the signaling for palette entries and palette indices is almost identical. In non-monochrome formats, each palette entry consists of three components. In monochrome formats, each palette entry consists of a single component. For subsampled chroma directions, chroma samples are associated with a luminance sample index divisible by 2. After reconstructing the CU's palette index, if a sample has only a single associated component, only the first component of the palette entry is used. The only difference in signaling lies in the escape component values. For each escape symbol, the number of escape component values ​​signaled may differ depending on the number of components associated with that symbol.

[0183] 2.6.4. Palette in Two Trees

[0184] In VVC, a dual-tree codec structure is used to encode and decode intra-frame stripes, so the luma component and the two chroma components may have different palettes and palette indices. Furthermore, the two chroma components share the same palette and palette index.

[0185] 2.6.5. Line-based CG Palette Mode

[0186] A line-based CG palette pattern is adopted in VVC. In this method, each CU of the palette pattern is divided into multiple segments of m samples based on the traversal scan pattern (m=16 in this test). The encoding order of the palette run-length encoding and decoding in each segment is as follows: For each pixel, a signaling instruction is given for one context-coded bit, run_copy_flag=0, indicating whether the pixel has the same pattern as the previous pixel, i.e., if the previously scanned pixel and the current pixel are both run-length type COPY_ABOVE, or if the previously scanned pixel and the current pixel are both run-length type INDEX and have the same index value. Otherwise, the signaling instruction is given for run_copy_flag=1. If the pixel has a different pattern than the previous pixel, a signaling instruction is given for one context-coded bit, copy_above_palette_indices_flag, indicating the run-length type of the pixel, i.e., INDEX or COPY_ABOVE. Similar to the Palette mode in VTM 6.0, the decoder does not need to resolve the run type if the sample is in the first row (horizontal traversal scan) or the first column (vertical traversal scan), due to the default use of INDEX mode. Furthermore, if the previously resolved run type is COPY_ABOVE, the decoder does not need to resolve the run type. After palette run encoding / decoding of pixels in a segment, the index values ​​(for INDEX mode) and quantized escape colors are bypassed and grouped separately from the encoding / decoding of binary bits in the context encoding / decoding to improve throughput within each line CG. Since the index values ​​are now encoded / decoded / decoded after run encoding / decoding, instead of before as in VTM, the encoder does not need to signal the number of index values ​​num_palette_indices_minus1 and the last run type copy_above_indices_for_final_run_flag.

[0187] 3. Technical problems solved by the embodiments and solutions described herein

[0188] In the current design, both ACT and luma BDPCM modes can be enabled for a block. However, for blocks encoded and decoded using ACT mode, chroma BDPCM mode is always disabled. Therefore, for luma and chroma blocks within the same codec unit, prediction signals can be derived differently, which may be inefficient.

[0189] When ACT is enabled, the block's quantization parameter (QP) can become negative.

[0190] The current design of ACT does not support lossless encoding and decoding.

[0191] The signaling used by ACT is independent of block size.

[0192] The maximum palette size and maximum predicted size are fixed numbers, which may limit the flexibility of the palette pattern.

[0193] The escaped samples are binarized using the third-order exponential-Golomb (EG) method, but the binarization of the escaped samples does not depend on the quantization parameter (QP).

[0194] 4. Technical Solutions

[0195] The technical solutions described below should be considered as examples for explaining general concepts. These technical solutions should not be interpreted narrowly. Furthermore, these technical solutions can be combined in any way.

[0196] In the following description, the term "block" can refer to a video region, such as a codec unit (CU), prediction unit (PU), or transform unit (TU), which may contain samples from the three color components. The term "BDPCM" is not limited to a design in VVC, but may refer to a technique that encodes and decodes residuals using different prediction signal generation methods.

[0197] Interaction between ACT and BDPCM (Projects 1-4)

[0198] 1. Whether to enable the chroma BDPCM mode may depend on the use of ACT and / or luminance BDPCM modes.

[0199] a. In one example, when ACT is enabled on a block, an indication of the use of the chroma BDPCM mode (e.g., intra_bdpcm_chroma_flag) can be inferred as an indication of the use of the luma BDPCM mode (e.g., intra_bdpcm_luma_flag).

[0200] i. In one example, the inferred value for the chroma BDPCM mode is defined as (ACT and luminance BDPCM modes enabled? True: False).

[0201] 1. In one example, when intra_bdpcm_luma_flag is false, intra_bdpcm_chroma_flag can be set to be equal to false.

[0202] a. Alternatively, when intra_bdpcm_luma_flag is true.

[0203] The intra_bdpcm_chroma_flag can be set to true.

[0204] ii. Alternatively, in one example, if the indication of the use of the block's luminance BDPCM mode and ACT is true, then the indication of the use of the chrominance BDPCM mode can be inferred to be true.

[0205] b. Alternatively, it may be conditionally checked whether the signaling notification block uses ACT, for example, whether the same BDPCM prediction direction is used for luminance and chrominance samples in the block.

[0206] i. Alternatively, in addition, after using BDPCM mode, signaling notifications are given indicating the use of ACT.

[0207] 2. When ACT is enabled on a block, the indication of the prediction direction of the chroma BDPCM mode (e.g., intra_bdpcm_chroma_dir_flag) can be inferred as the indication of the prediction direction of the luma BDPCM mode (e.g., intra_bdpcm_luma_dir_flag).

[0208] a. In one example, the inferred value of intra_bdpcm_chroma_dir_flag is defined as (ACT enabled? intra_bdpcm_luma_dir_flag: 0).

[0209] i. In one example, if the prediction direction indicator of the luminance BDPCM mode is horizontal, then the prediction direction indicator of the chrominance BDPCM mode can be inferred to be horizontal.

[0210] ii. Alternatively, in one example, if the prediction direction indicator of the luminance BDPCM mode is vertical, the prediction direction indicator of the chrominance BDPCM mode can be inferred to be vertical.

[0211] 3. ACT and BDPCM modes can be applied mutually exclusively.

[0212] a. In one example, when ACT mode is enabled on a block, BDPCM mode can be disabled on the block.

[0213] i. Alternatively, the signaling notification of the use of the ACT mode may follow the signaling notification of the use of the BDPCM mode.

[0214] ii. Alternatively, the indication of the use of the BDPCM mode may not be signaled and inferred as false (0).

[0215] b. In one example, when BDPCM mode is enabled on a block, ACT mode can be disabled on the block.

[0216] i. Alternatively, after signaling the indication for the use of BDPCM mode, the indication for the use of ACT mode may be signaled.

[0217] ii. Alternatively, the indication of the use of ACT mode may be notified by signaling and inferred as false (0).

[0218] c. In one example, the BDPCM mode in the above example can represent the luminance BDPCM mode and / or the chrominance BDPCM mode.

[0219] 4. Inverse ACT can be applied before inverse BDPCM at the decoder.

[0220] a. In one example, ACT can be applied even when the luminance BDPCM and chrominance BDPCM have different prediction modes.

[0221] b. Alternatively, at the encoder, a forward ACT can be applied after BDPCM.

[0222] QP settings when ACT is enabled (Item 5)

[0223] 5. It is proposed to prune QP when ACT is enabled.

[0224] a. In one example, the pruning function can be defined as (l, h, x), where l is the lowest possible value of the input x and h is the highest possible value of the input x.

[0225] i. In one example, l can be set to equal to 0.

[0226] ii. In one example, h can be set to equal 63.

[0227] b. In one example, QP can be the qP given in Section 2.5.

[0228] c. In one example, clipping can be performed after QP adjustments in ACT mode.

[0229] d. In one example, when transform skipping is applied, l can be set to be equal to the minimum allowed QP of the transform skipping mode.

[0230] Related palette patterns (Items 6-7)

[0231] 6. The values ​​of the maximum permissible palette size and / or the maximum permissible predicted size may depend on the codec characteristics. Assume that S1 is the maximum palette size (or palette predicted size) associated with the first codec characteristic; and S2 is the maximum palette size (or palette predicted size) associated with the second codec characteristic.

[0232] a. In one example, the encoding / decoding feature could be color components.

[0233] i. In one example, the maximum permissible palette size and / or the maximum permissible predicted value size for different color components may have different values.

[0234] ii. In one example, the maximum permissible palette size and / or maximum permissible predicted value size of the first color component (e.g., Y in YCbCr, G in RGB) may differ from the maximum permissible palette size and / or maximum permissible predicted value size of the other two color components that do not include the first color component (e.g., Cb and Cr in YCbCr, B and R in RGB).

[0235] b. In one example, the encoding / decoding feature could be the quantization parameter (QP).

[0236] i. In one example, if QP1 is greater than QP2, then S1 and / or S2 of QP1 should be less than S1 and / or S2 of QP2.

[0237] ii. In one example, a QP can be a strip-level QP or a block-level QP.

[0238] c. In one example, S2 can be greater than or equal to S1.

[0239] d. For the first and second codec features, the indication of the maximum palette size / palette prediction size can be signaled separately or inferred from one to the other.

[0240] i. In one example, S1 can be signaled and S2 can be derived from S1.

[0241] 1. In one example, S2 can be inferred as S1–n.

[0242] 2. In one example, S2 can be inferred as S1 >> n.

[0243] 3. In one example, S2 can be inferred as floor(S1 / n), where floor(x) represents the largest integer not greater than x.

[0244] e. In one example, S1 and / or S2 can be notified at a high level (e.g., SPS / PPS / PH / strip header) and adjusted at a low level (e.g., CU / block).

[0245] i. How to adjust S1 and / or S2 may depend on the encoding / decoding information.

[0246] 1. How to adjust S1 and / or S2 may depend on the current QP.

[0247] a. In one example, if the current QP increases, then S1 and / or S2 should be decreased.

[0248] 2. How to adjust S1 and / or S2 may depend on the block dimension.

[0249] a. In one example, if the current block size increases, then S1 and / or S2 should increase.

[0250] f.S1 and / or S2 may depend on whether LMCS is used.

[0251] 7. The parameters associated with the binarization method for the escaped sample / pixel may depend on encoding / decoding information, such as quantization parameters (QP).

[0252] a. In one example, the EG binarization method can be used, and the order of EG binarization, denoted by k, can depend on the encoding / decoding information.

[0253] i. In one example, k can be reduced as the current QP increases.

[0254] Signaling notification in ACT mode (Items 8-10)

[0255] 8. Signaling notifications can be provided at the sequence / video / strip / film / sub-picture / tile / other video processing unit level, or indications of the maximum and / or minimum allowed ACT size can be derived based on codec information.

[0256] a. In one example, they can be signaled in the SPS / PPS / image header / strip header.

[0257] b. In one example, they can be conditionally signaled, for example, based on the enabled ACT.

[0258] c. In one example, the maximum and / or minimum allowed ACT size N levels can be signaled / defined, for example, N=2.

[0259] i. In one example, the maximum and / or minimum allowed ACT size can be set to K0 or K1 (e.g., K0 = 64, K1 = 32).

[0260] ii. Alternatively, an indication of the signaling notification level may be provided, for example, a signaling notification flag when N=2.

[0261] d. In one example, signaling can be used to notify the difference between the maximum and / or minimum allowed ACT size and the maximum and / or minimum allowed transform (or transform skip) size (e.g., for the luma component).

[0262] e. In one example, the maximum and / or minimum allowed ACT size can be derived from the maximum and / or minimum (or transform skip) allowed size (e.g., for the luminance component).

[0263] f. Alternatively, in addition, whether and / or how signaling is used to inform ACT of instructions and other side information related to ACT may depend on the maximum and / or minimum allowed values.

[0264] 9. When a block is larger than the maximum allowed ACT size (or the maximum allowed transform size), the block can be automatically divided into multiple sub-blocks, where all sub-blocks share the same prediction mode (e.g., all sub-blocks are intra-coded), and ACT can be enabled at the sub-block level rather than the block level.

[0265] 10. Instructions for the use of ACT mode can be conditionally signaled based on block dimensions (e.g., block width and / or block height, block width multiplied by height, the ratio between block width and block height, the maximum / minimum value of block width and block height) and / or the maximum allowed ACT size.

[0266] a. In one example, when certain conditions are met (e.g., based on block dimensions), a signaling instruction for the use of ACT mode can be sent.

[0267] i. In one example, the condition is whether the current block width is less than or equal to m and / or the current block height is less than or equal to n.

[0268] ii. In one example, the condition is whether the current block width multiplied by its height is less than or greater than m.

[0269] iii. In one example, the condition is whether the current block width multiplied by its height is greater than or not less than m.

[0270] b. Alternatively, in one example, when certain conditions are not met (e.g., based on block dimensions)

[0271] At this time, it is possible to use the ACT mode without signaling.

[0272] i. In one example, the condition is whether the current block width is greater than m and / or the current block height is greater than n.

[0273] ii. In one example, the condition is whether the current block width multiplied by its height is less than or greater than m.

[0274] iii. In one example, the condition is whether the current block width multiplied by its height is greater than or not less than m.

[0275] iv. Alternatively, the indication of the use of the ACT pattern can be inferred as 0.

[0276] c. In the above example, variables m and n can be predefined (e.g., 4, 64, 128), or be signaled, or be inferred on the spot.

[0277] i. In one example, m and / or n can be derived from the decoded messages in the SPS / PPS / APS / CTU line / CTU group / CU / block.

[0278] 1. In one example, m and / or n can be set to be equal to the maximum allowed transformation size (e.g., MaxTbSizeY).

[0279] Signaling of constraint flags in general constraint information syntax (Items 11-16)

[0280] The following constraint flags can be signaled in video units other than SPS. For example, they can be signaled in the general constraint information syntax specified in JVET-P2001-vE.

[0281] 11. It is proposed to use constraint flags to specify whether the SPS ACT enable flag (e.g., sps_act_enabled_flag) can be equal to 0.

[0282] a. In one example, this flag could be represented as no_act_constraint_flag

[0283] i. When this flag is equal to 1, the SPS ACT enabled flag (e.g., sps_act_enabled_flag) is active.

[0284] It can be equal to 0.

[0285] ii. When this flag is equal to 0, it will not impose this constraint.

[0286] 12. It is proposed to use constraint flags to specify whether the SPS BDPCM enable flag (e.g., sps_bdpcm_enabled_flag) can be equal to 0.

[0287] a. In one example, this flag can be represented as no_bdpcm_constraint_flag.

[0288] i. When this flag is equal to 1, the SPS BDPCM enable flag is set (e.g., ...).

[0289] sps_bdpcm_enabled_flag) can be equal to 0.

[0290] ii. When this flag is equal to 0, it will not impose this constraint.

[0291] 13. It is proposed to use constraint flags to specify whether the SPS chroma BDPCM enable flag (e.g., sps_bdpcm_chroma_enabled_flag) can be equal to 0.

[0292] a. In one example, the flag can be represented as

[0293] no_bdpcm_chroma_constraint_flag.

[0294] i. When this flag is equal to 1, the SPS chromaticity BDPCM enable flag is activated (e.g., ...).

[0295] sps_bdpcm_chroma_enabled_flag) can be equal to 0.

[0296] ii. When this flag is equal to 0, it will not impose this constraint.

[0297] 14. It is proposed to use constraint flags to specify whether the SPS palette enabling flag (e.g., sps_palette_enabled_flag) can be equal to 0.

[0298] a. In one example, this flag can be represented as no_palette_constraint_flag.

[0299] i. When this flag is equal to 1, the SPS palette enable flag (e.g.)

[0300] sps_palette_enabled_flag) can be equal to 0.

[0301] ii. When this flag is equal to 0, it will not impose this constraint.

[0302] 15. It is proposed to use constraint flags to specify whether the SPS RPR enabling flag (e.g., ref_pic_resampling_enabled_flag) can be equal to 0.

[0303] a. In one example, the flag can be represented as

[0304] no_ref_pic_resampling_constraint_flag.

[0305] i. When this flag is equal to 1, the SPS RPR enable flag (e.g.)

[0306] The ref_pic_resampling_enabled_flag can be equal to 0.

[0307] ii. When this flag is equal to 0, it will not impose this constraint.

[0308] 16. In the examples above (bullets 11-15), such constraint flags can be conditionally signaled, for example, based on the chroma format (e.g., chroma_format_idc) and / or a separate planar codec or ChromaArrayType.

[0309] ACTQP Offset (Items 17-19)

[0310] 17. It is proposed that when applying ACT to a block, the ACT offset can be applied after applying other chroma offsets (e.g., chroma offsets in PPS and / or picture header (PH) and / or strip header (SH)).

[0311] 18. It is proposed that when applying YCgCo color transformation on a block, a PPS and / or PH offset other than -5 be set for JCbCr mode 2.

[0312] a. In one example, the offset can be a number other than -5.

[0313] b. In one example, the offset can be indicated in the PPS (e.g., as...).

[0314] pps_act_cbcr_qp_offset_plus6), and the offset can be set to

[0315] pps_act_cbcr_qp_offset_plus6-6.

[0316] c. In one example, the offset can be indicated in the PPS (e.g., as...).

[0317] pps_act_cbcr_qp_offset_plus7), and the offset can be set to pps_act_cbcr_qp_offset_plus7-7.

[0318] 19. When applying YCgCo-R on a block, it is proposed to set PPS and / or PH offsets for JCbCr mode 2 other than 1.

[0319] a. In one example, the offset can be a number other than -1.

[0320] b. In one example, the offset can be indicated in the PPS (e.g., as...).

[0321] pps_act_cbcr_qp_offset), and the offset can be set to pps_act_cbcr_qp_offset.

[0322] c. In one example, the offset can be indicated in the PPS (e.g., as...).

[0323] pps_act_cbcr_qp_offset_plus1), and the offset can be set to pps_act_cbcr_qp_offset_plus1-1.

[0324] General technologies (Projects 20-21)

[0325] 20. In the above example, S1, S2, l, h, m, n, and / or k are integers and may depend on a. the signaling notification message in DPS / SPS / VPS / PPS / APS / Picture Header / Strip Header / Piece Group Header / Maximum Codec Unit (LCU) / Codec Unit (CU) / LCU Line / LCU Group / TU / PU Block / Video Codec Unit.

[0326] b. Location of CU / PU / TU / block / video codec unit

[0327] c. Encoding / decoding mode for blocks containing samples along the edges

[0328] d. The transformation matrix applied to a block containing samples along its edges.

[0329] e. Block dimensions / block shape of the current block and / or its neighboring blocks

[0330] f. Color format specification (e.g., 4:2:0, 4:4:4, RGB, or YUV)

[0331] g. Encoding / decoding tree structures (e.g., dual-tree or single-tree)

[0332] h. Strip / Piece Type and / or Image Type

[0333] i. Color components (e.g., only applicable to Cb or Cr)

[0334] j. Time-domain layer ID

[0335] k. Standard grade / level / tier

[0336] l. Alternatively, S1, S2, l, h, m, n and / or k can be signaled to the decoder.

[0337] 21. The proposed methods can be applied under certain conditions.

[0338] a. In one example, the condition is that the color format is 4:2:0 and / or 4:2:2.

[0339] b. In one example, it can be at the sequence / image / strip / piece / tile / video region level (e.g.

[0340] The signaling notification in SPS / PPS / image header / strip header indicates the instructions for using the above methods.

[0341] c. In one example, the use of the above method may depend on

[0342] i. Video content (e.g., screen content or natural content)

[0343] ii. Signaling notification messages in DPS / SPS / VPS / PPS / APS / Picture header / Strip header / Piece group header / Maximum Codec Unit (LCU) / Codec Unit (CU) / LCU line / LCU group / TU / PU block / Video codec unit

[0344] iii. Location of CU / PU / TU / block / video codec unit

[0345] iv. Encoding / decoding modes for blocks containing samples along the edges

[0346] v. A transformation matrix applied to a block containing samples along its edges.

[0347] vi. Block dimensions of the current block and / or its neighboring blocks

[0348] vii. Block shape of the current block and / or its neighboring blocks

[0349] viii. Color format indication (e.g., 4:2:0, 4:4:4, RGB, or YUV)

[0350] ix. Encoding / decoding tree structures (e.g., dual-tree or single-tree)

[0351] x. Strip / group type and / or image type

[0352] xi. Color components (e.g., may only apply to Cb or Cr)

[0353] xii. Temporal layer ID

[0354] xiii. Standard grade / level / tier

[0355] xiv. Alternatively, m and / or n may be signaled to the decoder.

[0356] 5. Examples

[0357] This example is based on JVET-P2001-vE. Newly added text uses... Bold, Italic, Underlined Text Highlighted. Deleted text is marked with italic text.

[0358] 5.1 Example #1

[0359] This example involves the interaction between ACT and BDPCM modes.

[0360]

[0361]

[0362] 5.2. Example #2

[0363] This example involves the interaction between ACT and BDPCM modes.

[0364] An intra_bdpcm_chroma_flag value of 1 indicates that BDPCM is applied to the current chroma codec block at position (x0, y0), i.e., the transform is skipped. The intra-frame chroma prediction mode is specified by intra_bdpcm_chroma_dir_flag. An intra_bdpcm_chroma_flag value of 0 indicates that BDPCM is not applied to the current chroma codec block at position (x0, y0).

[0365] When intra_bdpcm_chroma_flag does not exist and When it is false, it is inferred to be equal to 0.

[0366]

[0367] For x0..x0+cbWidth-1, y=y0..y0+cbHeight-1 and cIdx=1..2, the variable BdpcmFlag[x][y][cIdx] is set to equal intra_bdpcm_chroma_flag.

[0368] An intra_bdpcm_chroma_dir_flag value of 0 specifies that the BDPCM prediction direction is horizontal. An intra_bdpcm_chroma_dir_flag value of 1 specifies that the BDPCM prediction direction is vertical.

[0369] The variable BdpcmDir[x][y][cIdx] is set to equal intra_bdpcm_chroma_dir_flag(x = x0..x0 + cbWidth-1, y = y0..y0 + cbHeight-1 and cIdx = 1..2).

[0370] 5.3. Example #3

[0371] This example relates to QP settings.

[0372] 8.7.3 Scaling process of transformation coefficients

[0373] The input for this process is:

[0374] – Specifies the brightness position (xTbY, yTbY) of the current brightness transformation block relative to the top-left brightness sample of the current image.

[0375] – The variable nTbW specifies the width of the transform block.

[0376] – The variable nTbH specifies the height of the transform block.

[0377] – The variable predMode specifies the prediction mode of the encoding / decoding unit.

[0378] – The variable cIdx specifies the color components of the current block.

[0379] The output of this process is an array d of (nTbW)×(nTbH) with scaling transformation coefficients of elements d[x][y].

[0380] …

[0381] The quantization parameter qP was modified, and the variables rectNonTsFlag and bdShift were derived as follows:

[0382] – If transform_skip_flag[xTbY][yTbY][cIdx] equals 0, then the following applies:

[0383] qP=qP-(cu_act_enabled_flag[xTbY][yTbY]?5:0) (1133)

[0384]

[0385] rectNonTsFlag=(((Log2(nTbW)+Log2(nTbH))&1)==1)? 1:0(1134)

[0386] bdShift=BitDepth+rectNonTsFlag+ (1135)

[0388] ((Log2(nTbW)+Log2(nTbH)) / 2)-5+pic_dep_quant_enabled_flag

[0389] – Otherwise (transform_skip_flag[xTbY][yTbY][cIdx] equals 1), the following applies:

[0390] qP=Max(QpPrimeTsMin,qP)-(cu_act_enabled_flag[xTbY][yTbY]?5:0)(1136)

[0391]

[0392] rectNonTsFlag = 0 (1137)

[0393] bdShift = 10 (1138)

[0394] …

[0395] 5.4. Example #4

[0396] 8.7.1 Derivation of Quantization Parameters

[0397] …

[0398] – The chromaticity parameters of the Cb and Cr components, Qp'Cb and Qp'Cr, and the joint Cb-Cr encoding / decoding Qp'CbCr are derived as follows:

[0399] Qp′Cb=Clip3(-QpBdOffset,63,qPCb+pps_cb_qp_offset+slice_cb_qp_offset+CuQpOffsetCb)+QpBdOffset (1122)

[0400] Qp′Cr=Clip3(-QpBdOffset,63,qPCr+pps_cr_qp_offset+slice_cr_qp_offset+CuQpOffsetCr)+QpBdOffset (1123)

[0401] Qp′CbCr=Clip3(-QpBdOffset,63,qPCbCr+pps_joint_cbcr_qp_offset+

[0402] slice_joint_cbcr_qp_offset+CuQpOffsetCbCr)+QpBdOffset (1124)

[0403] 5.5. Example #5

[0404] 7.3.9.5 Encoding / Decoding Unit Syntax

[0405]

[0406] K0 and K1 are set to equal 32.

[0407] 5.6. Example #6

[0408] 7.3.9.5 Encoding / Decoding Unit Syntax

[0409]

[0410] Figure 7 This is a block diagram illustrating an example video processing system 700, in which various techniques disclosed herein can be implemented. Various implementations may include some or all of the components of system 700. System 700 may include an input 702 for receiving video content. The video content may be received in a raw or uncompressed format, such as 8 or 10-bit multi-component pixel values, or in a compressed or encoded format. Input 702 may represent a network interface, a peripheral bus interface, or a storage interface. Examples of network interfaces include wired interfaces such as Ethernet, Passive Optical Networking (PON), etc., and wireless interfaces such as Wi-Fi or cellular interfaces.

[0411] System 700 may include an encoding / decoding component 704, which can implement the various encoding / decoding or coding methods described in this document. Encoding / decoding component 704 can reduce the average bit rate of the video from input 702 to the output of encoding / decoding component 704 to produce an encoded / decoded representation of the video. Therefore, encoding / decoding techniques are sometimes referred to as video compression or video transcoding techniques. The output of encoding / decoding component 704 can be stored or transmitted via communication through the connection represented by component 706. The stored or transmitted bitstream (or encoded / decoded) representation of the video received at input 702 can be used by component 708 to generate pixel values ​​or displayable video to be sent to display interface 710. The process of generating user-visible video from the bitstream representation is sometimes referred to as video decompression. Furthermore, although some video processing operations are referred to as “encoding / decoding” operations or tools, it will be understood that encoding tools or operations are used at the encoder, and the corresponding decoding tools or operations will be performed by the decoder to reverse the encoded result.

[0412] Examples of peripheral bus interfaces or display interfaces may include Universal Serial Bus (USB), High Definition Multimedia Interface (HDMI), or DisplayPort. Examples of storage interfaces include Serial Advanced Technology Attachment (SATA), Peripheral Component Interconnect (PCI), Integrated Drive Electronic Devices (IDE), etc. The technologies described in this document can be embodied in a variety of electronic devices, such as mobile phones, laptops, smartphones, or other devices capable of performing digital data processing and / or video display.

[0413] Figure 8 This is a block diagram of a video processing apparatus 800. Apparatus 800 can be used to implement one or more methods described herein. Apparatus 800 can be embodied in smartphones, tablets, computers, Internet of Things (IoT) receivers, etc. Apparatus 800 may include one or more processors 802, one or more memories 804, and video processing hardware 806. Processor 802 can be configured to implement one or more methods described in this document. One or more memories 804 can be used to store data and code for implementing the methods and techniques described herein. Video processing hardware 806 can be used to implement some of the techniques described in this document in hardware circuitry. In some embodiments, hardware 806 may be partially or wholly located within processor 802 (e.g., a graphics processor).

[0414] Figure 9 This is a block diagram illustrating an example video codec system 100 that can utilize the techniques disclosed herein. Figure 9 As shown, the video encoding / decoding system 100 may include a source device 110 and a destination device 120. The source device 110 generates encoded video data, which may be referred to as a video encoding device. The destination device 120 can decode the encoded video data generated by the source device 110, which may be referred to as a video decoding device. The source device 110 may include a video source 112, a video encoder 114, and an input / output (I / O) interface 116.

[0415] Video source 112 may include sources such as video capture devices, interfaces for receiving video data from video content providers, and / or computer graphics systems for generating video data, or combinations of these sources. Video data may include one or more images. Video encoder 114 encodes the video data from video source 112 to generate a bitstream. The bitstream may include a sequence of bits forming a codec representation of the video data. The bitstream may include codec images and associated data. A codec image is a codec representation of an image. Associated data may include sequence parameter sets, image parameter sets, and other syntax structures. I / O interface 116 may include a modulator / demodulator (modem) and / or a transmitter. Encoded video data may be transmitted directly to destination device 120 via network 130a through I / O interface 116. Encoded video data may also be stored on storage medium / server 130b for access by destination device 120.

[0416] Destination device 120 may include I / O interface 126, video decoder 124 and display device 122.

[0417] I / O interface 126 may include a receiver and / or a modem. I / O interface 126 may acquire encoded video data from source device 110 or storage medium / server 130b. Video decoder 124 may decode the encoded video data. Display device 122 may display the decoded video data to a user. Display device 122 may be integrated with destination device 120, or may be located external to destination device 120, which is configured to engage with an external display device.

[0418] The video encoder 114 and the video decoder 124 can operate according to video compression standards such as the High Efficiency Video Codec (HEVC) standard, the Universal Video Codec (VVM) standard, and other current and / or external standards.

[0419] Figure 10 This is a block diagram illustrating an example of a video encoder 200, which can be... Figure 9 The video encoder 114 in the system 100 shown.

[0420] The video encoder 200 can be configured to perform any or all of the techniques disclosed herein. Figure 10 In the example, the video encoder 200 includes multiple functional components. The techniques described in this disclosure can be shared among the various components of the video encoder 200. In some examples, the processor can be configured to perform any or all of the techniques described in this disclosure.

[0421] The functional components of the video encoder 200 may include a segmentation unit 201, a prediction unit 202 (which may include a mode selection unit 203), a motion estimation unit 204, a motion compensation unit 205, an intra-frame prediction unit 206, a residual generation unit 207, a transform unit 208, a quantization unit 209, an inverse quantization unit 210, an inverse transform unit 211, a reconstruction unit 212, a buffer 213, and an entropy coding unit 214.

[0422] In other examples, the video encoder 200 may include more, fewer, or different functional components. In one example, the prediction unit 202 may include an intra-block copy (IBC) unit. The IBC unit can perform prediction in IBC mode, where at least one reference picture is the picture containing the current video block.

[0423] Furthermore, some components, such as the motion estimation unit 204 and the motion compensation unit 205, can be highly integrated, but for illustrative purposes, in Figure 10 The examples are represented separately.

[0424] The segmentation unit 201 can segment an image into one or more video blocks. The video encoder 200 and the video decoder 300 can support various video block sizes.

[0425] The mode selection unit 203 can, for example, select one of the encoding / decoding modes, intra-frame or inter-frame, based on the error result, and provide the resulting intra-frame or inter-frame encoded / decoded block to the residual generation unit 207 to generate residual block data, and provide it to the reconstruction unit 212 to reconstruct the coded block for use as a reference picture. In some examples, the mode selection unit 203 can select a combination of intra-frame prediction and inter-frame prediction (CIIP) modes, where the prediction is based on the inter-frame prediction signal and the intra-frame prediction signal. The mode selection unit 203 can also select the resolution of the motion vector for the block (e.g., sub-pixel or integer pixel precision) in the case of inter-frame prediction.

[0426] To perform inter-frame prediction on the current video block, motion estimation unit 204 can generate motion information for the current video block by comparing one or more reference frames from buffer 213 with the current video block. Motion compensation unit 205 can determine the predicted video block for the current video block based on the motion information and decoded samples of the images from buffer 213 (excluding the images associated with the current video block).

[0427] The motion estimation unit 204 and the motion compensation unit 205 may, for example, perform different operations on the current video block depending on whether the current video block is in an I-strip, P-strip, or B-strip.

[0428] In some examples, motion estimation unit 204 can perform unidirectional prediction on the current video block, and can search for a reference video block for the current video block in the reference images of list 0 or list 1. Then, motion estimation unit 204 can generate a reference index indicating the reference image in list 0 or list 1 containing the reference video block, and a motion vector indicating the spatial displacement between the current video block and the reference video block. Motion estimation unit 204 can output the reference index, prediction direction indicator, and motion vector as motion information for the current video block. Motion compensation unit 205 can generate a predicted video block for the current block based on the reference video block indicated by the motion information of the current video block.

[0429] In other examples, motion estimation unit 204 can perform bidirectional prediction on the current video block. Motion estimation unit 204 can search for a reference video block for the current video block in the reference images in list 0, and can also search for another reference video block for the current video block in the reference images in list 1. Motion estimation unit 204 can then generate a reference index indicating the reference images in lists 0 and 1 that contain the reference video blocks, and a motion vector indicating the spatial displacement between the reference video blocks and the current video block. Motion estimation unit 204 can output the reference index and motion vector of the current video block as the motion information of the current video block. Motion compensation unit 205 can generate a predicted video block for the current video block based on the reference video blocks indicated by the motion information of the current video block.

[0430] In some examples, the motion estimation unit 204 can output a complete set of motion information for the decoder's decoding processing.

[0431] In some examples, motion estimation unit 204 may not output a complete set of motion information for the current video. Instead, motion estimation unit 204 may signal the motion information of the current video block by referencing the motion information of another video block. For example, motion estimation unit 204 may determine that the motion information of the current video block is sufficiently similar to the motion information of neighboring video blocks.

[0432] In one example, the motion estimation unit 204 may indicate a value in the syntax structure associated with the current video block that indicates to the video decoder 300 that the current video block has the same motion information as another video block.

[0433] In another example, motion estimation unit 204 can identify another video block and motion vector difference (MVD) within the syntactic structure associated with the current video block. The motion vector difference indicates the difference between the motion vector of the current video block and the motion vector of the indicated video block. Video decoder 300 can use the motion vector of the indicated video block and the motion vector difference to determine the motion vector of the current video block.

[0434] As discussed above, the video encoder 200 can predictively signal motion vectors. Two examples of predictive signaling techniques that can be implemented by the video encoder 200 include Advanced Motion Vector Prediction (AMVP) and merge pattern signaling.

[0435] Intra-prediction unit 206 can perform intra-prediction on the current video block. When intra-prediction unit 206 performs intra-prediction on the current video block, it can generate prediction data for the current video block based on decoded samples from other video blocks in the same frame. The prediction data for the current video block may include the predicted video block and various syntax elements.

[0436] The residual generation unit 207 can generate residual data for the current video block by subtracting (e.g., indicated by a minus sign) the predicted video block from the current video block. The residual data for the current video block can include residual video blocks corresponding to different sample components in the current video block.

[0437] In other examples, such as in skip mode, there may be no residual data for the current video block, and the residual generation unit 207 may not perform the subtraction operation.

[0438] The transform processing unit 208 can generate one or more transform coefficient video blocks for the current video block by applying one or more transforms to the residual video blocks associated with the current video block.

[0439] After the transform processing unit 208 generates a transform coefficient video block associated with the current video block, the quantization unit 209 can quantize the transform coefficient video block associated with the current video block based on one or more quantization parameter (QP) values ​​associated with the current video block.

[0440] Inverse quantization unit 210 and inverse transform unit 211 can apply inverse quantization and inverse transform to the transform coefficient video block, respectively, to reconstruct the residual video block based on the transform coefficient video block. Reconstruction unit 212 can add the reconstructed residual video block to the corresponding samples of one or more predicted video blocks generated by prediction unit 202 to generate a reconstructed video block associated with the current block, which is then stored in buffer 213.

[0441] After the video block is reconstructed by the reconstruction unit 212, a loop filtering operation can be performed to reduce video block artifacts in the video block.

[0442] Entropy encoding unit 214 can receive data from other functional components of video encoder 200. When entropy encoding unit 214 receives data, it can perform one or more entropy encoding operations to generate entropy encoded data and output a bit stream including the entropy encoded data.

[0443] Figure 11 This is a block diagram illustrating an example of a video decoder 300, which can be... Figure 9 The video decoder 114 in the system 100 shown.

[0444] The video decoder 300 can be configured to perform any or all of the technologies disclosed herein. Figure 11 In the example, the video decoder 300 includes multiple functional components. The techniques described in this disclosure can be shared among the various components of the video decoder 300. In some examples, the processor can be configured to perform any or all of the techniques described in this disclosure.

[0445] exist Figure 11 In the example, the video decoder 300 includes an entropy decoding unit 301, a motion compensation unit 302, an intra-frame prediction unit 303, an inverse quantization unit 304, an inverse transform unit 305, a reconstruction unit 306, and a buffer 307. In some examples, the video decoder 300 can perform functions typically associated with the video encoder 200. Figure 10 The encoding process described is the opposite of the decoding process.

[0446] The entropy decoding unit 301 can retrieve the encoded bitstream. The encoded bitstream may include entropy-coded video data (e.g., encoded blocks of video data). The entropy decoding unit 301 can decode the entropy-coded video data, and the motion compensation unit 302 can determine motion information from the entropy-decoded video data, including motion vectors, motion vector precision, reference image list index, and other motion information. For example, the motion compensation unit 302 can determine this information by executing AMVP and merge modes.

[0447] The motion compensation unit 302 can generate motion compensation blocks, possibly performing interpolation based on an interpolation filter. Identifiers for the interpolation filters used at sub-pixel precision can be included in the syntax elements.

[0448] The motion compensation unit 302 can use the interpolation filter used by the video encoder 20 during video block encoding to calculate the interpolation of sub-integer pixels of the reference block. The motion compensation unit 302 can determine the interpolation filter used by the video encoder 200 based on the received syntax information, and use the interpolation filter to generate the prediction block.

[0449] The motion compensation unit 302 may use some syntax information to determine the size of the blocks used to encode the frames and / or stripes of the encoded video sequence, segmentation information describing how each macroblock of the image of the encoded video sequence is segmented, a mode indicating how each partition is encoded, one or more reference frames (and a list of reference frames) for each inter-frame coded block, and other information used to decode the encoded video sequence.

[0450] Intra-prediction unit 303 can use, for example, an intra-prediction mode received in the bitstream to form prediction blocks based on spatially adjacent blocks. Inverse quantization unit 303 performs inverse quantization (i.e., dequantization) on the quantized video block coefficients provided in the bitstream and decoded by entropy decoding unit 301. Inverse transform unit 303 applies an inverse transform.

[0451] The reconstruction unit 306 can sum the residual block with the corresponding prediction block generated by the motion compensation unit 202 or the intra-frame prediction unit 303 to form a decoded block. If necessary, a deblocking filter can also be applied to filter the decoded block to remove block artifacts. The decoded video block is then stored in a buffer 307, which provides a reference block for subsequent motion compensation / intra-frame prediction and also generates decoded video for presentation on a display device.

[0452] Figure 12-24 Example methods for implementing the above technical solutions are shown, for example, Figure 7-11 The embodiment shown.

[0453] Figure 12 A flowchart of an example method 1200 for video processing is shown. At operation 1210, method 1200 includes determining the maximum and / or minimum allowable size of an adaptive color transformation (ACT) mode for encoding and decoding the current video block for the conversion between the current video block and the video bitstream.

[0454] At operation 1220, method 1200 includes performing a transformation based on determination.

[0455] Figure 13 A flowchart of an example method 1300 for video processing is shown. At operation 1310, method 1300 includes determining a maximum allowed palette size and / or a minimum allowed prediction size for a palette mode used to encode and decode the current video block for the conversion between the current video block and the video bitstream, the maximum allowed palette size and / or minimum allowed prediction size being based on the encoding and decoding characteristics of the current video block.

[0456] At operation 1320, method 1300 includes performing a transformation based on determination.

[0457] Figure 14 A flowchart of an example method 1400 for video processing is shown. At operation 1410, method 1400 includes performing a conversion between a current video block of video and a bitstream of video, the current video block being encoded and decoded using a palette-mode codec tool, and the bitstream conforming to a format rule that specifies parameters associated with the binarization of the escaped symbols of the current video block in the bitstream based on the encoding and decoding information of the current video block.

[0458] Figure 15 A flowchart of an example method 1500 for video processing is shown. At operation 1510, method 1500 includes determining, for the conversion between video comprising blocks and a bitstream of video, that the size of the blocks is greater than the maximum permissible size of the Adaptive Color Transformation (ACT) mode.

[0459] At operation 1520, method 1500 includes performing a transformation based on determination, and in response to the block size being larger than the maximum allowed size of the ACT mode, the block is divided into multiple sub-blocks, each of the multiple sub-blocks sharing the same prediction mode, and the ACT mode being enabled at the sub-block level.

[0460] Figure 16 A flowchart of an example method 1600 for video processing is shown. At operation 1610, method 1600 includes performing a conversion between a current video block of video and a bitstream of video, the bitstream conforming to a format rule that specifies whether a signaling indication in the bitstream to use an adaptive color transformation (ACT) mode for the current video block is based on at least one of the dimensions of the current video block or the maximum allowed size of the ACT mode.

[0461] Figure 17 A flowchart of an example method 1700 for video processing is shown. At operation 1710, method 1700 includes performing a conversion between the current video unit of the video and a bitstream of the video that conforms to a format rule specifying whether a first flag is included in the bitstream, and the first flag indicating whether a second flag in the sequence parameter set (SPS) specifies that the adaptive color transformation (ACT) mode of the current video unit is disabled.

[0462] Figure 18 A flowchart of an example method 1800 for video processing is shown. At operation 1810, method 1800 includes performing a conversion between the current video unit of the video and a bitstream of the video that conforms to a format rule specifying whether a first flag is included in the bitstream, and the first flag indicating whether a second flag in the sequence parameter set (SPS) specifies that the block-based incremental pulse code modulation (BDPCM) mode of the current video unit is disabled.

[0463] Figure 19 A flowchart of an example method 1900 for video processing is shown. At operation 1910, method 1900 includes performing a conversion between the current video unit of the video and a bitstream of the video that conforms to a format rule specifying whether a first flag is included in the bitstream, and whether a second flag in the sequence parameter set (SPS) specifies that the block-based incremental pulse code modulation (BDPCM) mode for the chroma component of the current video unit is disabled.

[0464] Figure 20A flowchart of an example method 2000 for video processing is shown. At operation 2010, method 2000 includes performing a conversion between the current video unit of the video and the bitstream of the video, the bitstream conforming to a format rule specifying whether a first flag is included in the bitstream, and the first flag indicating whether a second flag in the sequence parameter set (SPS) specifies that the palette of the current video unit is disabled.

[0465] Figure 21 A flowchart of an example method 2100 for video processing is shown. At operation 2110, method 2100 includes performing a conversion between the current video unit of the video and a bitstream of the video that conforms to a format rule specifying whether a first flag is included in the bitstream, and whether a second flag in the sequence parameter set (SPS) specifies that the reference picture resampling (RPR) mode of the current video unit is disabled.

[0466] Figure 22 A flowchart of an example method 2200 for video processing is shown. At operation 2210, method 2200 includes performing a conversion between the current video block and the video bitstream according to a rule that specifies the application of an additional quantization parameter offset when the Adaptive Color Transform (ACT) mode is enabled for the current video block.

[0467] Figure 23 A flowchart of an example method 2300 for video processing is shown. At operation 2310, method 2300 includes performing a conversion between a current video block and a bitstream representation of the video according to a rule, wherein the current video block is encoded using a joint CbCr encoding / decoding mode, wherein a YCgCo color transform or an inverse YCgCo color transform is applied to the current video block, and the rule specifies that: since the current video block is encoded using a joint CbCr encoding / decoding mode in which a YCgCo color transform is used, a quantization parameter offset value other than -5 is used in the picture header (PH) or picture parameter set (PPS) associated with the current video block.

[0468] Figure 24 A flowchart of an example method 2400 for video processing is shown. At operation 2410, method 2400 includes performing a conversion between a current video block and a bitstream representation of the video according to a rule, wherein the current video block is encoded and decoded using a joint CbCr encoding / decoding mode, wherein a YCgCo-R color transform or an inverse YCgCo-R color transform is applied to the current video block, and the rule specifies that: since the current video block is encoded and decoded using a joint CbCr encoding / decoding mode in which a YCgCo-R color transform is used, a quantization parameter offset value different from a predetermined offset is used in the picture header (PH) or picture parameter set (PPS) associated with the current video block.

[0469] Below is a list of preferred solutions for some embodiments.

[0470] A1. A video processing method comprising determining a maximum and / or minimum permissible size of an adaptive color transformation (ACT) mode for encoding and decoding the current video block, for a conversion between a current video block and a bitstream of the video; and performing the conversion based on the determination.

[0471] A2. According to the method of solution A1, the maximum or minimum allowed size of the ACT mode is based on the maximum or minimum allowed size of the color component transform block or transform skip block.

[0472] A3. According to the method of solution A2, where the color component is the luminance component.

[0473] A4. According to the method of solution A1, the signaling notification of the ACT mode is based on the maximum or minimum size allowed in the bitstream.

[0474] A5. According to the method of solution A1, the side information related to the ACT mode is signaled in the bitstream based on the maximum or minimum allowed size.

[0475] A6. According to the method of solution A1, the signaling in the sequence parameter set (SPS), picture parameter set (PPS), picture header or strip header indicates the maximum or minimum allowed size.

[0476] A7. According to the method of solution A1, when ACT mode is enabled, signaling in the bitstream indicates whether the maximum size or the minimum size is allowed.

[0477] A8. According to the method of solution A1, where the maximum allowed size is K0 and the minimum allowed size is K1, and where K0 and K1 are positive integers.

[0478] A9. According to the method of solution A8, where K0 = 64 and K1 = 32.

[0479] A10. According to the method of solution A1, the signaling in the bitstream informs the difference between the maximum or minimum allowed size of the ACT codec block and the corresponding size of the transform block or transform skip block.

[0480] A11. A video processing method comprising determining a maximum allowed palette size and / or a minimum allowed prediction size for a palette mode used to encode and decode the current video block for a conversion between a current video block and a bitstream of the video; and performing the conversion based on the determination, wherein the maximum allowed palette size and / or the minimum allowed prediction size are based on the encoding and decoding characteristics of the current video block.

[0481] A12. According to the method of solution A11, where the encoding and decoding characteristics are the color components of the video, and where the maximum permissible palette size is different for different color components.

[0482] A13. According to the method of solution A11, the encoding and decoding characteristics are quantization parameters.

[0483] A14. According to the method of solution A11, wherein S1 is the maximum permissible palette size or minimum permissible prediction size associated with the first codec feature, and S2 is the maximum permissible palette size or minimum permissible prediction size associated with the second codec feature, and wherein S1 and S2 are positive integers.

[0484] A15. The method described in solution A14, wherein S2 is greater than or equal to S1.

[0485] A16. According to the method of solution A14, S1 and S2 are signaled separately in the bit stream.

[0486] A17. According to the method of solution A14, S1 is signaled in the bit stream, and S2 is inferred or derived from S1.

[0487] A18. According to the method of solution A17, where S2 = S1 - n, where n is a non-zero integer.

[0488] A19. According to the method of solution A14, S1 and S2 are notified by signaling at the first level, and S1 and S2 are adjusted at the second level, which is lower than the first level.

[0489] A20. According to the method of solution A19, the first level is sequence level, picture level or stripe level, and the second level is codec unit level or block level.

[0490] A21. According to the method of solution A14, S1 and S2 are based on whether the luminance mapping with chroma scaling (LMCS) is applied to the current video block.

[0491] A22. A video processing method comprising performing a conversion between a current video block and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the current video block is encoded and decoded using a palette-mode encoding / decoding tool, and wherein the format rule specifies parameters associated with the binarization of escaped symbols of the current video block in the bitstream based on encoding / decoding information of the current video block.

[0492] A23. According to the method of solution A22, the encoding / decoding information includes one or more quantization parameters.

[0493] A24. The method of solution A22, wherein binarization uses the exponential Golomb binarization method of order k, where k is a non-negative integer based on the encoded / decoded information.

[0494] A25. A video processing method comprising determining, for a conversion between a video comprising a block and a bitstream of the video, that the size of the block is greater than the maximum permissible size of an adaptive color transformation (ACT) mode; and performing a conversion based on the determination, wherein, in response to the block size being greater than the maximum permissible size of the ACT mode, the block is divided into a plurality of sub-blocks, and wherein each sub-block in the plurality of sub-blocks shares the same prediction mode, and the ACT mode is enabled at the sub-block level.

[0495] A26. A video processing method comprising performing a conversion between a current video block and a bitstream of the video, wherein the bitstream conforms to a format rule specifying whether to signal in the bitstream an indication of using an adaptive color transformation (ACT) mode on the current video block based on at least one of the dimensions of the current video block or the maximum permissible size of the ACT mode.

[0496] A27. According to the method of solution A26, where the signaling notification indicates that the width of the current video block is less than or equal to m or the height of the current video block is less than or equal to n, where m and n are positive integers.

[0497] A28. According to the method of solution A26, since the product of the width and height of the current video block is less than or equal to m, a signaling notification is issued, where m is a positive integer.

[0498] A29. According to the method of solution A26, where no signaling notification indication is given because the width of the current video block is greater than m or the height of the current video block is greater than n, where m and n are positive integers.

[0499] A30. According to any one of the solutions A27 to A29, where m is predefined.

[0500] A31. The method according to any one of solutions A27 to A29, wherein m is derived based on the sequence parameter set (SPS), picture parameter set (PPS), adaptive parameter set (APS), codec tree unit (CTU) row, CTU group, codec unit (CU) or block.

[0501] A32. According to the method of solution A26, the indication is not notified by signaling and is inferred to be zero.

[0502] The following is another list of preferred solutions for some of the embodiments.

[0503] B1. A video processing method comprising performing a conversion between a current video unit of a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies whether a first flag is included in the bitstream, and wherein the first flag indicates whether a second flag in a sequence parameter set (SPS) specifies whether an adaptive color transformation (ACT) mode of the current video unit is disabled.

[0504] B2. According to the method of solution B1, the first flag includes general constraint information of one or more images in the output layer set of the video.

[0505] B3. According to the method of solution B1 or B2, where the first flag is no_act_constraint_flag, and where the second flag is sps_act_enabled_flag.

[0506] B4. According to any of the solutions B1 to B3, where the second flag is equal to zero because the first flag is equal to one.

[0507] B5. According to any one of solutions B1 to B3, wherein the second flag equal to zero indicates that ACT mode is disabled for the current video unit.

[0508] B6. According to any of the solutions B1 to B3, the second flag may be equal to zero or one, since the first flag is equal to zero.

[0509] B7. A video processing method comprising performing a conversion between a current video unit of a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies whether a first flag is included in the bitstream, and wherein the first flag indicates whether a second flag in a sequence parameter set (SPS) specifies whether a block-based incremental pulse codec modulation (BDPCM) mode of the current video unit is disabled.

[0510] B8. According to the method of solution B7, wherein the first flag includes general constraint information of one or more images in the output layer set of the video.

[0511] B9. According to the method of solution B7 or B8, where the first flag is no_bdpcm_constraint_flag, and where the second flag is sps_bdpcm_enabled_flag.

[0512] B10. According to any of the solutions B7 to B9, where the first flag is equal to one and the second flag is equal to zero.

[0513] B11. According to any of the solutions B7 to B9, wherein the second flag equal to zero indicates that the BDPCM mode is disabled for the current video unit.

[0514] B12. According to any of the solutions B7 to B9, where since the first flag is equal to zero, the second flag can be equal to zero or one.

[0515] B13. A video processing method comprising performing a conversion between a current video unit of a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies whether a first flag is included in the bitstream, and wherein the first flag indicates whether a second flag in a sequence parameter set (SPS) specifies a block-based incremental pulse codec modulation (BDPCM) mode that disables the chroma component of the current video unit.

[0516] B14. According to the method of solution B13, wherein the first flag includes general constraint information of one or more pictures in the output layer set of the video.

[0517] B15. According to the method of solution B13 or B14, where the first flag is no_bdpcm_chroma_constraint_flag, and where the second flag is sps_bdpcm_chroma_enabled_flag.

[0518] B16. According to any one of solutions B13 to B15, where the second flag is equal to zero since the first flag is equal to one.

[0519] B17. According to any one of solutions B13 to B15, wherein the second flag equal to zero specifies that BDPCM mode is disabled for the chroma component of the current video unit.

[0520] B18. According to any of the solutions B13 to B15, wherein since the first flag is equal to zero, the second flag may be equal to zero or one.

[0521] B19. A video processing method comprising performing a conversion between a current video unit of a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies whether a first flag is included in the bitstream, and wherein the first flag indicates whether a second flag in a sequence parameter set (SPS) specifies whether a palette mode of the current video unit is disabled.

[0522] B20. According to the method of solution B19, wherein the first flag includes general constraint information of one or more pictures in the output layer set of the video.

[0523] B21. According to the method of solution B19 or B20, where the first flag is no_palette_constraint_flag, and where the second flag is sps_palette_enabled_flag.

[0524] B22. According to any of the solutions B19 to B21, where the second flag is equal to zero since the first flag is equal to one.

[0525] B23. According to any of the solutions B19 to B21, wherein the second flag equal to zero specifies that the palette mode is disabled for the current video unit.

[0526] B24. According to any of the solutions B19 to B21, wherein since the first flag is equal to zero, the second flag may be equal to zero or one.

[0527] B25. A video processing method comprising performing a conversion between a current video unit of a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies whether a first flag is included in the bitstream, and wherein the first flag indicates whether a second flag in a sequence parameter set (SPS) specifies whether a reference picture resampling (RPR) mode for the current video unit is disabled.

[0528] B26. According to the method of solution B25, wherein the first flag includes general constraint information of one or more pictures in the output layer set of the video.

[0529] B27. According to the method of solution B25 or B26, where the first flag is no_ref_pic_resampling_constraint_flag, and where the second flag is ref_pic_resampling_enabled_flag.

[0530] B28. According to any one of solutions B25 to B27, where the second flag is equal to zero since the first flag is equal to one.

[0531] B29. According to any one of solutions B25 to B27, wherein the second flag equal to zero indicates that RPR mode is disabled for the current video unit.

[0532] B30. According to any of the solutions B25 to B27, wherein since the first flag is equal to zero, the second flag may be equal to zero or one.

[0533] B31. According to any one of solutions B1 to B30, wherein the format rules further specify whether the first flag is conditionally indicated in the bitstream for signaling notification.

[0534] B32. According to the method of solution B31, where the condition is the type of chroma format of the video.

[0535] The following is another list of preferred solutions for some embodiments.

[0536] C1. A video processing method comprising performing a conversion between a current video block and a bitstream of video according to a rule specifying the application of an additional quantization parameter offset when an adaptive color transformation (ACT) mode is enabled for the current video block.

[0537] C2. Based on the method of solution C1, wherein an additional quantization parameter offset is applied after applying one or more chromaticity offsets.

[0538] C3. According to the method of solution C2, one or more chromaticity offsets are specified in the Picture Parameter Set (PPS), Picture Header (PH), or Strip Header (SH).

[0539] C4. A video processing method comprising performing a conversion between a current video block and a bitstream representation of a video according to rules, wherein the current video block is encoded using a joint CbCr encoding / decoding mode, wherein a YCgCo color transform or an inverse YCgCo color transform is applied to the current video block, and wherein the rules specify that: since the current video block is encoded using a joint CbCr encoding / decoding mode in which the YCgCo color transform is used, a quantization parameter offset value different from -5 is used in the picture header (PH) or picture parameter set (PPS) associated with the current video block.

[0540] C5. According to the method of solution C4, the joint CbCr mode includes JCbCr mode 2.

[0541] C6. A video processing method comprising performing a conversion between a current video block and a bitstream representation of a video according to rules, wherein the current video block is encoded and decoded using a joint CbCr encoding / decoding mode, wherein a YCgCo-R color transform or an inverse YCgCo-R color transform is applied to the current video block, and wherein the rules specify that: since the current video block is encoded and decoded using a joint CbCr encoding / decoding mode in which a YCgCo-R color transform is used, a quantization parameter offset value different from a predetermined offset is used in the picture header (PH) or picture parameter set (PPS) associated with the current video block.

[0542] C7. According to the method of solution C6, the joint CbCr mode includes JCbCr mode 2.

[0543] C8. According to the method of solution C6 or C7, where the predetermined offset is 1.

[0544] C9. According to the method of solution C6 or C7, where the predetermined offset is -1.

[0545] The following is another list of preferred solutions for some embodiments.

[0546] P1. A video processing method comprising determining whether to enable a chroma block-based incremental pulse codec modulation (BDPCM) mode for a video block based on whether the use of an adaptive color transformation (ACT) mode and / or a luminance BDPCM mode for the video block is enabled; and performing a conversion between the video block and a bitstream representation of the video based on the determination.

[0547] P2. According to the method of solution P1, the signaling of the first value of the first flag associated with enabling the chroma BDPCM mode is determined based on the signaling of the ACT mode enabled for the video block and the signaling of the second value of the second flag associated with the use of the luma BDPCM mode.

[0548] P3. According to the method of solution P2, the first value of the first flag is false in response to the ACT mode being enabled and the second value of the second flag is false.

[0549] P4. According to the method of solution P2, the first value of the first flag has a true value in response to the second value of the second flag.

[0550] P5. According to the method of solution P1, the signaling of the ACT mode of the video block is conditionally based on the same BDPCM prediction direction for the luminance and chrominance samples of the video block.

[0551] P6. According to the method of solution P5, the signaling of ACT mode is indicated after the signaling of chroma BDPCM mode and luminance BDPCM mode.

[0552] P7. According to the method of solution P1, in response to the use of ACT mode being enabled, the first value of the first prediction direction of the first prediction direction of the chromaticity BDPCM mode is derived based on the second value of the second prediction direction of the luminance BDPCM mode.

[0553] P8. According to the method of solution P7, the first value of the first prediction direction of the chromaticity BDPCM mode is the same as the second value of the second prediction direction of the luminance BDPCM mode.

[0554] P9. According to the method in solution P8, the first prediction direction of the chromaticity BDPCM mode and the second prediction direction of the luminance BDPCM mode are in the horizontal direction.

[0555] P10. According to the method in solution P8, the first prediction direction of the chromaticity BDPCM mode and the second prediction direction of the luminance BDPCM mode are in the vertical direction.

[0556] P11. According to the method of solution P1, in response to the use of ACT mode being disabled, the first value indicating the first prediction direction of the chromatic BDPCM mode is zero.

[0557] P12. A video processing method, comprising determining whether a block-based incremental pulse codec modulation (BDPCM) mode is enabled for a video block based on whether the use of an adaptive color transformation (ACT) mode based on video blocks is enabled; and performing a conversion between the video blocks and a bitstream representation of the video based on the determination.

[0558] P13. According to the method in solution P12, in response to enabling ACT mode for video blocks, BDPCM mode is disabled for video blocks.

[0559] P14. According to the method of solution P13, the signaling notifies the first flag indicating the BDPCM mode after the second flag indicating the ACT mode.

[0560] P15. According to the method of solution P13, where there is no signaling notification indicating a flag for BDPCM mode, where the flag is determined to be a false value or zero.

[0561] P16. According to the method in solution P12, in response to enabling BDPCM mode for video blocks, ACT mode is disabled for video blocks.

[0562] P17. According to the method of solution P16, the signaling notifies the first flag indicating the BDPCM mode before the second flag indicating the ACT mode.

[0563] P18. According to the method of solution P16, where there is no signaling notification indicating the flag of ACT mode, where the flag is determined to be a false value or zero.

[0564] P19. According to any one of the solutions P12 to P18, wherein the BDPCM mode includes a luminance BDPCM mode and / or a chrominance BDPCM mode.

[0565] P20. According to the method of solution P1, where the ACT mode is applied when the chromaticity BDPCM mode and the luminance BDPCM mode are associated with different prediction modes.

[0566] P21. According to the method of solution P20, a forward ACT mode is applied after either the chroma BDPCM mode or the luminance BDPCM mode.

[0567] P22. According to any one of the solutions P1 to P21, wherein, in response to the ACT mode being enabled, the quantization parameters (QP) of the video block are clipped.

[0568] P23. According to the method in solution P22, the pruning function used for pruning QP is defined as (l,h,x), where l is the lowest possible value of input x and h is the highest possible value of input x.

[0569] P24. According to the method in solution P23, where l equals zero.

[0570] P25. According to the method in solution P23, where h equals 63.

[0571] P26. According to the method in solution P22, after adjusting the QP for ACT mode, the QP of the video block is trimmed.

[0572] P27. According to the method in solution P23, where, in response to transform skip being applied to the video block, l is equal to the minimum allowed QP of the transform skip mode.

[0573] P28. According to any of the methods in solutions P23 to P26, where l, h, m, n and / or k are integers that depend on (i) the signaling notification message in DPS / SPS / VPS / PPS / APS / Picture Header / Strip Header / Piece Group Header / Maximum Codec Unit (LCU) / Codec Unit (CU) / LCU Line / LCU Group / TU / PU Block / Video Codec Unit, (ii) the location of the CU / PU / TU / Block / Video Codec Unit, and (iii) the block containing samples along the edge. The encoding / decoding mode, (iv) the transform matrix applied to the block containing samples along the edge, (v) the block size / block shape of the current block and / or its neighboring blocks, (vi) the color format (e.g., 4:2:0, 4:4:4, RGB or YUV), (vii) the encoding / decoding tree structure (e.g., dual-tree or single-tree), (viii) the stripe / piece group type and / or picture type, (ix) the color components (e.g., can only be applied to Cb or Cr), (x) the temporal layer ID, or (xi) the standard profile / level / hierarchy.

[0574] P29. According to any one of the solutions P23 to P26, wherein l, h, m, n and / or k are signaled to the decoder.

[0575] P30. According to the method of solution P30, the color format is 4:2:0 or 4:2:2.

[0576] P31. According to any one of the solutions P1 to P30, wherein signaling at the sequence, picture, strip, slice, tile or video region level indicates ACT mode or BDPCM mode or chroma BDPCM mode or luminance BDPCM mode.

[0577] The following technical solutions are applicable to any of the solutions mentioned above.

[0578] O1. The method according to any of the foregoing solutions, wherein the conversion includes decoding the video according to the bitstream representation.

[0579] O2. The method according to any of the foregoing solutions, wherein the conversion includes encoding the video into a bitstream representation.

[0580] O3. The method according to any of the preceding claims, wherein the conversion includes generating a bitstream from the current video unit, and the method further includes storing the bitstream in a non-transitory computer-readable recording medium.

[0581] O4. A method for storing a bitstream representing a video to a computer-readable recording medium, comprising generating a bitstream from a video according to the method described in any of the preceding claims; and writing the bitstream to the computer-readable recording medium.

[0582] O5. A video processing apparatus, comprising a processor configured to implement the method described in any of the preceding claims.

[0583] O6. A computer-readable medium having instructions stored thereon that, when executed, cause a processor to perform the method described in any of the preceding claims.

[0584] O7. A computer-readable medium storing a bitstream representation generated according to any of the preceding claims.

[0585] O8. A video processing apparatus for storing a bitstream representation, wherein the video processing apparatus is configured to implement the method described in any of the preceding claims.

[0586] O9. A bitstream generated using the method described herein, which is stored on a computer-readable medium.

[0587] In this document, the term "video processing" can refer to video encoding, video decoding, video compression, or video decompression. For example, a video compression algorithm can be applied during the conversion from a pixel representation of a video to its corresponding bitstream representation, and vice versa. For example, the bitstream representation of the current video block can correspond to bits that are co-located or scattered at different locations within the bitstream, as defined by the syntax. For example, macroblocks can be encoded based on the error residuals from the transform and encoding / decoding, and can also be encoded using bits in the header and other fields in the bitstream.

[0588] The disclosures and other solutions, examples, embodiments, modules, and functional operations described in this document can be implemented in digital electronic circuits, or in computer software, firmware, or hardware (including the structures disclosed in this document and their structural equivalents), or in one or more combinations thereof. The disclosed embodiments and other embodiments can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer-readable medium for execution by or control of the operation of a data processing device. The computer-readable medium can be a machine-readable storage device, a machine-readable storage substrate, a storage device, a composition of substances influencing machine-readable propagation signals, or one or more combinations thereof. The term "data processing device" includes all devices, apparatuses, and machines for processing data, such as programmable processors, computers, or multiple processors or computers. In addition to hardware, the device may also include code that creates an execution environment for the computer program in question, such as code constituting processor firmware, a protocol stack, a database management system, an operating system, or one or more combinations thereof. Propagation signals are artificially generated signals, such as machine-generated electrical, optical, or electromagnetic signals, which are generated to encode information for transmission to a suitable receiver device.

[0589] Computer programs (also known as programs, software, software applications, scripts, or code) can be written in any programming language, including compiled or interpreted languages, and can be deployed in any form, including as standalone programs or modules, components, subroutines, or other units suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a file portion that holds other programs or data (e.g., one or more scripts stored in a markup language document), a single file dedicated to the program in question, or multiple coordination files (e.g., files storing one or more modules, subroutines, or code portions). A computer program can be deployed to execute on a single computer or on multiple computers located at a single site or distributed across multiple sites and interconnected by a communication network.

[0590] The processes and logic flows described in this document can be executed by one or more programmable processors, which execute one or more computer programs to perform functions by manipulating input data and generating outputs. Processes and logic flows can also be executed by dedicated logic circuits, and devices can be implemented as dedicated logic circuits, such as FPGAs (Field-Programmable Gate Arrays) or ASICs (Application-Specific Integrated Circuits).

[0591] Processors suitable for executing computer programs include, for example, general-purpose microprocessors and special-purpose microprocessors, as well as any one or more processors in any type of digital computer. Typically, a processor receives instructions and data from read-only memory or random access memory, or both. The basic components of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Typically, a computer will also include one or more mass storage devices (e.g., magnetic disks, magneto-optical disks, or optical disks) for storing data, or operatively coupled to receive data from or transfer data to or from them, or both. However, a computer does not need to have such devices. Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media, and memory devices, including, for example, semiconductor memory devices such as EPROM, EEPROM, and flash memory devices; magnetic disks, such as internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and memory may be supplemented by or integrated into special-purpose logic circuitry.

[0592] Although this patent document contains numerous details, these details should not be construed as limiting the scope of any subject matter or potentially claimed content, but rather as a description of features that may be specific to particular embodiments of a particular technology. Certain features described in this patent document within the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented separately in multiple embodiments or in any suitable sub-combination. Furthermore, although features may be described above as functioning in certain combinations, and even initially stated so, in some cases one or more features may be removed from the declared combinations, and the declared combinations may refer to sub-combinations or variations thereof.

[0593] Similarly, although operations are depicted in a specific order in the accompanying drawings, this should not be construed as requiring such operations to be performed in the specific order or sequence shown, or requiring all shown operations to be performed to obtain the desired result. Furthermore, the separation of various system components in the embodiments described in this patent document should not be construed as requiring such separation in all embodiments.

[0594] Only a few implementations and examples are described, and other implementations, enhancements and variations may be made based on what is described and illustrated in this patent document.

Claims

1. A method of processing video data, comprising: performing a conversion between a current video unit of a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies whether a first flag is included in the bitstream, the first flag comprising general constraint information of one or more pictures in an output layer set of the video; and wherein the first flag indicates whether a second flag in a sequence parameter set (SPS) specifies to disable a resampling mode of the current video unit; wherein the first flag is denoted as no_ref_pic_resampling_constraint_flag, and wherein the second flag is denoted as ref_pic_resampling_enabled_flag; wherein the format rule further specifies whether a sixth flag is included in the bitstream, wherein the sixth flag comprises third general constraint information of one or more pictures in an output layer set of the video; wherein the sixth flag indicates whether a seventh flag in the SPS specifies to disable a palette mode of the current video unit; and wherein the sixth flag is denoted as no_palette_constraint_flag, and wherein the seventh flag is denoted as sps_palette_enabled_flag.

2. The method of claim 1, wherein, due to the first flag being equal to one, the second flag is equal to zero, wherein the second flag being equal to zero specifies to disable the resampling mode for the current video unit.

3. The method of claim 1, wherein, the format rule further specifies whether a third flag is included in the bitstream, wherein the third flag comprises second general constraint information of one or more pictures in an output layer set of the video; and wherein the third flag indicates whether a fourth flag in the SPS specifies to disable a block-based delta pulse code modulation (BDPCM) mode of the current video unit.

4. The method of claim 3, wherein, the third flag is denoted as no_bdpcm_constraint_flag, and wherein the fourth flag is denoted as sps_bdpcm_enabled_flag.

5. The method of claim 3, wherein, due to the third flag being equal to one, the fourth flag is equal to zero, wherein the fourth flag being equal to zero specifies to disable the block-based delta pulse code modulation mode for the current video unit.

6. The method of claim 3, wherein, the third flag indicates whether a fifth flag in the SPS specifies to disable a block-based delta pulse code modulation mode of a chroma component of the current video unit.

7. The method of claim 1, wherein, due to the sixth flag being equal to one, the seventh flag is equal to zero, and wherein the seventh flag being equal to zero specifies to disable the palette mode for the current video unit.

8. The method of claim 1, wherein, the format rule further specifies whether an eighth flag is included in the bitstream, wherein the eighth flag comprises fourth general constraint information of one or more pictures in an output layer set of the video, wherein the eighth flag indicates whether a ninth flag in the SPS specifies to disable an adaptive color transform (ACT) mode of the current video unit.

9. The method of claim 8, wherein, The eighth flag is denoted as no_act_constraint_flag, and wherein the ninth flag is denoted as sps_act_enabled_flag.

10. The method of claim 8, wherein, The ninth flag is equal to zero due to the eighth flag being equal to one, wherein the ninth flag being equal to zero specifies that the adaptive color transform mode is disabled for the current video unit.

11. The method of claim 1, wherein, The format rule further specifies whether the first flag is conditionally signaled in the bitstream.

12. The method of claim 1, further comprising: wherein The format rule further specifies whether the eighth flag is included in the bitstream, and wherein the eighth flag indicates whether a ninth flag in a sequence parameter set (SPS) specifies that a block-based delta pulse code modulation (BDPCM) mode for chroma components of the current video unit is disabled.

13. The method of claim 12, wherein, The eighth flag comprises general constraint information of one or more pictures in an output layer set of the video.

14. The method of claim 12, wherein, The eighth flag is no_bdpcm_chroma_constraint_flag, and wherein the ninth flag is sps_bdpcm_chroma_enabled_flag.

15. The method of claim 12, wherein, The ninth flag is equal to zero due to the eighth flag being equal to one.

16. The method of claim 12, wherein, The ninth flag being equal to zero specifies that the BDPCM mode is disabled for the chroma components of the current video unit.

17. The method of claim 12, wherein, The ninth flag is equal to zero or one due to the eighth flag being equal to zero.

18. The method of claim 12, wherein, The format rule further specifies whether the eighth flag is conditionally signaled in the bitstream based on a condition.

19. The method of claim 18, wherein, The condition is a type of chroma format of the video.

20. The method of any one of claims 1 to 19, wherein, The conversion comprises generating the bitstream from the current video unit, and wherein the method further comprises: storing the bitstream in a non-transitory computer-readable storage medium.

21. The method of any one of claims 1 to 19, wherein, The conversion comprises encoding the video into the bitstream.

22. The method of any one of claims 1 to 19, wherein, The conversion comprises decoding the video from the bitstream.

23. An apparatus for processing video data, comprising a processor and a non-transitory memory having instructions thereon, wherein, The instructions, when executed by the processor, cause the processor to: perform a conversion between a current video unit of a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies whether a first flag is included in the bitstream, the first flag comprising general constraint information of one or more pictures in an output layer set of the video; and wherein the first flag indicates whether a second flag in a sequence parameter set (SPS) specifies that a resampling mode for the current video unit is disabled; wherein the first flag is denoted as no_ref_pic_resampling_constraint_flag, and wherein the second flag is denoted as ref_pic_resampling_enabled_flag; wherein the format rule further specifies whether a sixth flag is included in the bitstream, wherein the sixth flag comprises third general constraint information of one or more pictures in an output layer set of the video; wherein the sixth flag indicates whether a seventh flag in a sequence parameter set (SPS) specifies that a block-based delta pulse code modulation (BDPCM) mode for chroma components of the current video unit is disabled. wherein the sixth flag indicates whether a seventh flag in a sequence parameter set (SPS) specifies disabling palette mode for the current video unit; and wherein the sixth flag is denoted as no_palette_constraint_flag, and wherein the seventh flag is denoted as sps_palette_enabled_flag.

24. The apparatus of claim 23, wherein, The first flag is denoted as no_ref_pic_resampling_constraint_flag, wherein the second flag is denoted as ref_pic_resampling_enabled_flag, wherein the second flag is equal to zero due to the first flag being equal to one, and wherein the second flag being equal to zero specifies disabling the resampling mode for the current video unit.

25. A non-transitory computer-readable storage medium storing instructions that cause a processor to: perform a conversion between a current video unit of a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies whether a first flag is included in the bitstream, the first flag comprising general constraint information of one or more pictures in an output layer set of the video; and wherein the first flag indicates whether a second flag in a sequence parameter set (SPS) specifies disabling a resampling mode for the current video unit; wherein the first flag is denoted as no_ref_pic_resampling_constraint_flag, and wherein the second flag is denoted as ref_pic_resampling_enabled_flag; wherein the format rule further specifies whether a sixth flag is included in the bitstream, wherein the sixth flag comprises third general constraint information of one or more pictures in an output layer set of the video; wherein the sixth flag indicates whether a seventh flag in a sequence parameter set (SPS) specifies disabling palette mode for the current video unit; and wherein the sixth flag is denoted as no_palette_constraint_flag, and wherein the seventh flag is denoted as sps_palette_enabled_flag.

26. A non-transitory computer-readable storage medium storing a bitstream of a video, the bitstream generated by a method performed by a video processing apparatus, wherein, The method comprises: generating a bitstream for a current video unit of a video, the bitstream conforms to a format rule, wherein the format rule specifies whether a first flag is included in the bitstream, the first flag comprising general constraint information of one or more pictures in an output layer set of the video; and wherein the first flag indicates whether a second flag in a sequence parameter set (SPS) specifies disabling a resampling mode for the current video unit; wherein the first flag is denoted as no_ref_pic_resampling_constraint_flag, and wherein the second flag is denoted as ref_pic_resampling_enabled_flag; wherein the format rule further specifies whether a sixth flag is included in the bitstream, wherein the sixth flag comprises third general constraint information of one or more pictures in an output layer set of the video; wherein the sixth flag indicates whether a seventh flag in a sequence parameter set (SPS) specifies disabling palette mode for the current video unit; and wherein the sixth flag is denoted as no_palette_constraint_flag, and wherein the seventh flag is denoted as sps_palette_enabled_flag. wherein the format rule further specifies whether a sixth flag is included in the bitstream, wherein the sixth flag comprises third general constraint information of one or more pictures in an output layer set of the video; wherein the sixth flag indicates whether a seventh flag in a sequence parameter set (SPS) specifies disabling palette mode for the current video unit; and wherein the sixth flag is denoted as no_palette_constraint_flag, and wherein the seventh flag is denoted as sps_palette_enabled_flag.

27. A method of storing a bitstream representing a video, comprising: generating a bitstream for a current video unit of a video, storing the bitstream into a non-transitory computer-readable storage medium, wherein the bitstream conforms to a format rule, wherein the format rule specifies whether a first flag is included in the bitstream, the first flag comprising general constraint information of one or more pictures in an output layer set of the video; and wherein the first flag indicates whether a second flag in a sequence parameter set (SPS) specifies disabling resampling mode for the current video unit; wherein the first flag is denoted as no_ref_pic_resampling_constraint_flag, and wherein the second flag is denoted as ref_pic_resampling_enabled_flag; wherein the format rule further specifies whether a sixth flag is included in the bitstream, wherein the sixth flag comprises third general constraint information of one or more pictures in an output layer set of the video; wherein the sixth flag indicates whether a seventh flag in a sequence parameter set (SPS) specifies disabling palette mode for the current video unit; and wherein the sixth flag is denoted as no_palette_constraint_flag, and wherein the seventh flag is denoted as sps_palette_enabled_flag.

28. A method of storing a bitstream representing a video into a computer-readable storage medium, comprising: generating a bitstream from a video according to the method of any one or more of claims 1 to 22; and writing the bitstream to the computer-readable storage medium.

29. A video processing apparatus comprising a processor configured to implement a method recited in any one or more of claims 1 to 22.

30. A computer-readable medium having stored thereon instructions that, when executed, cause a processor to implement a method recited in one or more of claims 1 to 22.

31. A computer-readable medium storing the bitstream representation generated according to any one or more of claims 1 to 22. The video processing apparatus is configured to implement a method recited in any one or more of claims 1 to 22.

32. A video processing apparatus that stores a bitstream representation, wherein, ​

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