Patent Description:
This disclosure relates to video encoding and video decoding.

<NPL> discloses aligning signalling of all syntax elements related to joint chrominance component residual coding (JCCR) with each other's and make it depending of JCCR control flag, and simplifying specification text in part of quantization control parameters signalling at slice header level.

<NPL> discloses supporting a default table without explicit signalling, such that for most use cases an encoder is not required to put the same luma-to-chroma QP table repeatedly in the bitstreams, and conditioning the signalling and derivation of the joint CbCr table based on whether the joint CbCr residual coding tool is enabled or not.

Optional features are set forth in the description.

In general techniques of this disclosure are directed to techniques for signaling parameters for joint coding of chroma residuals when coding of video data. Residual data for a chroma block may be separately signaled as a Cb residual block and a Cr residual block. However, in some examples, the Cb residual block and the Cr residual block may be jointly signaled in what is referred to as a joint chroma coding mode. In the joint chroma coding mode, a video encoder may encode a single joint chroma residual block and a video coder may derive a Cb residual block and a Cr residual block from the single joint chroma residual block.

The availability of the joint chroma coding mode may be controlled by one or more syntax elements. For instance, a video coder may signal a syntax element in a parameter set a that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data referring to the parameter set (e.g., sps_joint_cbcr_enabled_flag).

A video coder may signal mapping tables that provide parameters for deriving chroma quantization parameter (QP) from a collocated/corresponding luma QP. The video coder may signal multiple mapping tables that may be used in different scenarios. For instance, the video coder may signal a Cb mapping table, a Cr mapping table, and a joint Cb-Cr mapping table. However, arrangements that always signal all three mapping tables may not be efficient. For instance, where joint coding of chroma residuals is not enabled, it may not be necessary to signal the joint Cb-Cr mapping table, as such a table will not be used.

As discussed in further details below, <NPL>") proposed for the signaling of the mapping tables to be based on the syntax element that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data. In particular, JVET-P0426 allows for a video coder to avoid signaling the joint Cb-Cr mapping table where joint coding of chroma residuals is not enabled.

However, the arrangement in JVET-P0426 may present one or more disadvantages. In particular, as specified in JVET-P0426, the mapping tables are parsed from the bitstream before the syntax element that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data. As such, the alleged ability to avoid signaling the joint Cb-Cr mapping table may not be realized.

In accordance with one or more techniques of this disclosure, a video coder may be configured to parse a syntax element that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data. As such, if the syntax element indicates that joint coding of chroma residuals is not enabled, the video coder may avoid signaling/parsing the joint Cb-Cr mapping table. In this way, the techniques of this disclosure may improve the coding efficiency of video data (e.g., reduce the number of bits used to represent video data).

As discussed above, a video coder may signal a syntax element in a parameter set a that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data referring to the parameter set. In addition, the video coder may signal one or more other syntax elements that specify various parameters for the joint chroma coding mode (e.g., pps_joint_cbcr_qp_offset and joint_cber_qp_offset_list[ i ]). For instance, the video coder may signal a syntax element that specifies an offset to be applied to a luma QP when deriving a chroma QP. In some examples, the signalling of the syntax element that specifies an offset to be applied to a luma QP when deriving a chroma QP may be dependent on the value of the syntax element that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data.

The video coder may parse these syntax elements from a parameter set that is different than the parameter set from which the syntax element that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data. For instance, the video coder may signal the syntax element that specifies an offset to be applied to a luma QP when deriving a chroma QP in a picture parameter set (PPS) and signal the syntax element that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data in a sequence parameter set (SPS). However, one design principal of video coding may be to avoid parsing dependency. Coding the syntax element that specifies an offset to be applied to a luma QP when deriving a chroma QP in a PPS based on the value of the syntax element that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data in a SPS may violate this design principal.

In accordance with one or more techniques of this disclosure, as opposed to signaling syntax elements in the PPS that specify parameters for the joint chroma coding mode as being dependent on the syntax element in the SPS that specifies whether the joint chroma coding mode is enabled, a video coder may signal a syntax element in the PPS that specifies whether the syntax elements that specify parameters for the joint chroma coding mode are present in the PPS (e.g., pps_joint_cbcr_qp_offset_present_flag). While the value of the syntax element in the PPS that specifies whether the syntax elements that specify parameters for the joint chroma coding mode are present in the PPS may be at least semi redundant over the syntax element in the SPS that that specifies whether the joint chroma coding mode is enabled, signaling this additional syntax element may eliminate the parameter set interdependency, which may be desirable.

<FIG> is a block diagram illustrating an example video encoding and decoding system <NUM> that may perform the techniques of this disclosure. The techniques of this disclosure are generally directed to coding (encoding and/or decoding) video data. In general, video data includes any data for processing a video. Thus, video data may include raw, unencoded video, encoded video, decoded (e.g., reconstructed) video, and video metadata, such as signaling data.

As shown in <FIG>, system <NUM> includes a source device <NUM> that provides encoded video data to be decoded and displayed by a destination device <NUM>, in this example. In particular, source device <NUM> provides the video data to destination device <NUM> via a computer-readable medium <NUM>. Source device <NUM> and destination device <NUM> may comprise any of a wide range of devices, including desktop computers, notebook (i.e., laptop) computers, tablet computers, set-top boxes, telephone handsets such as smartphones, televisions, cameras, display devices, digital media players, video gaming consoles, video streaming device, or the like. In some cases, source device <NUM> and destination device <NUM> may be equipped for wireless communication, and thus may be referred to as wireless communication devices.

In the example of <FIG>, source device <NUM> includes video source <NUM>, memory <NUM>, video encoder <NUM>, and output interface <NUM>. Destination device <NUM> includes input interface <NUM>, video decoder <NUM>, memory <NUM>, and display device <NUM>. In accordance with this disclosure, video encoder <NUM> of source device <NUM> and video decoder <NUM> of destination device <NUM> may be configured to apply the techniques for quantization parameter signaling for joint chroma residual mode. Thus, source device <NUM> represents an example of a video encoding device, while destination device <NUM> represents an example of a video decoding device. In other examples, a source device and a destination device may include other components or arrangements. For example, source device <NUM> may receive video data from an external video source, such as an external camera. Likewise, destination device <NUM> may interface with an external display device, rather than include an integrated display device.

System <NUM> as shown in <FIG> is merely one example. In general, any digital video encoding and/or decoding device may perform techniques for quantization parameter signaling for joint chroma residual mode. Source device <NUM> and destination device <NUM> are merely examples of such coding devices in which source device <NUM> generates coded video data for transmission to destination device <NUM>. This disclosure refers to a "coding" device as a device that performs coding (encoding and/or decoding) of data. Thus, video encoder <NUM> and video decoder <NUM> represent examples of coding devices, in particular, a video encoder and a video decoder, respectively. In some examples, source device <NUM> and destination device <NUM> may operate in a substantially symmetrical manner such that each of source device <NUM> and destination device <NUM> includes video encoding and decoding components. Hence, system <NUM> may support one-way or two-way video transmission between source device <NUM> and destination device <NUM>, e.g., for video streaming, video playback, video broadcasting, or video telephony.

In general, video source <NUM> represents a source of video data (i.e., raw, unencoded video data) and provides a sequential series of pictures (also referred to as "frames") of the video data to video encoder <NUM>, which encodes data for the pictures. Video source <NUM> of source device <NUM> may include a video capture device, such as a video camera, a video archive containing previously captured raw video, and/or a video feed interface to receive video from a video content provider. As a further alternative, video source <NUM> may generate computer graphics-based data as the source video, or a combination of live video, archived video, and computer-generated video. In each case, video encoder <NUM> encodes the captured, pre-captured, or computer-generated video data. Video encoder <NUM> may rearrange the pictures from the received order (sometimes referred to as "display order") into a coding order for coding. Video encoder <NUM> may generate a bitstream including encoded video data. Source device <NUM> may then output the encoded video data via output interface <NUM> onto computer-readable medium <NUM> for reception and/or retrieval by, e.g., input interface <NUM> of destination device <NUM>.

Memory <NUM> of source device <NUM> and memory <NUM> of destination device <NUM> represent general purpose memories. In some examples, memories <NUM>, <NUM> may store raw video data, e.g., raw video from video source <NUM> and raw, decoded video data from video decoder <NUM>. Additionally or alternatively, memories <NUM>, <NUM> may store software instructions executable by, e.g., video encoder <NUM> and video decoder <NUM>, respectively. Although memory <NUM> and memory <NUM> are shown separately from video encoder <NUM> and video decoder <NUM> in this example, it should be understood that video encoder <NUM> and video decoder <NUM> may also include internal memories for functionally similar or equivalent purposes. Furthermore, memories <NUM>, <NUM> may store encoded video data, e.g., output from video encoder <NUM> and input to video decoder <NUM>. In some examples, portions of memories <NUM>, <NUM> may be allocated as one or more video buffers, e.g., to store raw, decoded, and/or encoded video data.

Computer-readable medium <NUM> may represent any type of medium or device capable of transporting the encoded video data from source device <NUM> to destination device <NUM>. In one example, computer-readable medium <NUM> represents a communication medium to enable source device <NUM> to transmit encoded video data directly to destination device <NUM> in real-time, e.g., via a radio frequency network or computer-based network. Output interface <NUM> may modulate a transmission signal including the encoded video data, and input interface <NUM> may demodulate the received transmission signal, according to a communication standard, such as a wireless communication protocol. The communication medium may comprise any wireless or wired communication medium, such as a radio frequency (RF) spectrum or one or more physical transmission lines. The communication medium may form part of a packet-based network, such as a local area network, a wide-area network, or a global network such as the Internet. The communication medium may include routers, switches, base stations, or any other equipment that may be useful to facilitate communication from source device <NUM> to destination device <NUM>.

In some examples, source device <NUM> may output encoded data from output interface <NUM> to storage device <NUM>. Similarly, destination device <NUM> may access encoded data from storage device <NUM> via input interface <NUM>. Storage device <NUM> may include any of a variety of distributed or locally accessed data storage media such as a hard drive, Blu-ray discs, DVDs, CD-ROMs, flash memory, volatile or non-volatile memory, or any other suitable digital storage media for storing encoded video data.

In some examples, source device <NUM> may output encoded video data to file server <NUM> or another intermediate storage device that may store the encoded video generated by source device <NUM>. Destination device <NUM> may access stored video data from file server <NUM> via streaming or download. File server <NUM> may be any type of server device capable of storing encoded video data and transmitting that encoded video data to the destination device <NUM>. File server <NUM> may represent a web server (e.g., for a website), a File Transfer Protocol (FTP) server, a content delivery network device, or a network attached storage (NAS) device. Destination device <NUM> may access encoded video data from file server <NUM> through any standard data connection, including an Internet connection. This may include a wireless channel (e.g., a Wi-Fi connection), a wired connection (e.g., digital subscriber line (DSL), cable modem, etc.), or a combination of both that is suitable for accessing encoded video data stored on file server <NUM>. File server <NUM> and input interface <NUM> may be configured to operate according to a streaming transmission protocol, a download transmission protocol, or a combination thereof.

Output interface <NUM> and input interface <NUM> may represent wireless transmitters/receivers, modems, wired networking components (e.g., Ethernet cards), wireless communication components that operate according to any of a variety of IEEE <NUM> standards, or other physical components. In examples where output interface <NUM> and input interface <NUM> comprise wireless components, output interface <NUM> and input interface <NUM> may be configured to transfer data, such as encoded video data, according to a cellular communication standard, such as <NUM>, <NUM>-LTE (Long-Term Evolution), LTE Advanced, <NUM>, or the like. In some examples where output interface <NUM> comprises a wireless transmitter, output interface <NUM> and input interface <NUM> may be configured to transfer data, such as encoded video data, according to other wireless standards, such as an IEEE <NUM> specification, an IEEE <NUM> specification (e.g., ZigBee™), a Bluetooth™ standard, or the like. In some examples, source device <NUM> and/or destination device <NUM> may include respective system-on-a-chip (SoC) devices. For example, source device <NUM> may include an SoC device to perform the functionality attributed to video encoder <NUM> and/or output interface <NUM>, and destination device <NUM> may include an SoC device to perform the functionality attributed to video decoder <NUM> and/or input interface <NUM>.

Input interface <NUM> of destination device <NUM> receives an encoded video bitstream from computer-readable medium <NUM> (e.g., a communication medium, storage device <NUM>, file server <NUM>, or the like). The encoded video bitstream may include signaling information defined by video encoder <NUM>, which is also used by video decoder <NUM>, such as syntax elements having values that describe characteristics and/or processing of video blocks or other coded units (e.g., slices, pictures, groups of pictures, sequences, or the like). Display device <NUM> displays decoded pictures of the decoded video data to a user. Display device <NUM> may represent any of a variety of display devices such as a cathode ray tube (CRT), a liquid crystal display (LCD), a plasma display, an organic light emitting diode (OLED) display, or another type of display device.

Video coding standards include ITU-T H. <NUM>, ISO/IEC MPEG-<NUM> Visual, ITU-T H. <NUM> or ISO/IEC MPEG-<NUM> Visual, ITU-T H. <NUM>, ISO/IEC MPEG-<NUM> Visual (MPEG-<NUM> Part <NUM>), ITU-T H. <NUM> (also known as ISO/IEC MPEG-<NUM> AVC), including its Scalable Video Coding (SVC) and Multiview Video Coding (MVC) extensions and ITU-T H. <NUM> (also known as ISO/IEC MPEG-<NUM> HEVC) with its extensions. During the April <NUM> meeting of the Joint Video Experts Team (JVET), the Versatile Video Coding (VVC) standardization activity (also known as ITU-T H. <NUM>) was kicked off with the evaluation of the video compression technologies submitted to the Call for Proposals.

Video encoder <NUM> and video decoder <NUM> may operate according to a video coding standard, such as ITU-T H. <NUM>, also referred to as High Efficiency Video Coding (HEVC) or extensions thereto, such as the multi-view and/or scalable video coding extensions. Alternatively, video encoder <NUM> and video decoder <NUM> may operate according to other proprietary or industry standards, such as the Joint Exploration Test Model (JEM) or ITU-T H. <NUM>, also referred to as Versatile Video Coding (VVC). A recent draft of the VVC standard is described in <NPL>"). The techniques of this disclosure, however, are not limited to any particular coding standard.

As another example, video encoder <NUM> and video decoder <NUM> may be configured to operate according to JEM or VVC. According to JEM or VVC, a video coder (such as video encoder <NUM>) partitions a picture into a plurality of coding tree units (CTUs). Video encoder <NUM> may partition a CTU according to a tree structure, such as a quadtree-binary tree (QTBT) structure or Multi-Type Tree (MTT) structure. The QTBT structure removes the concepts of multiple partition types, such as the separation between CUs, PUs, and TUs of HEVC. A QTBT structure includes two levels: a first level partitioned according to quadtree partitioning, and a second level partitioned according to binary tree partitioning. A root node of the QTBT structure corresponds to a CTU. Leaf nodes of the binary trees correspond to coding units (CUs).

In an MTT partitioning structure, blocks may be partitioned using a quadtree (QT) partition, a binary tree (BT) partition, and one or more types of triple tree (TT) (also called ternary tree (TT)) partitions. A triple or ternary tree partition is a partition where a block is split into three sub-blocks. In some examples, a triple or ternary tree partition divides a block into three sub-blocks without dividing the original block through the center. The partitioning types in MTT (e.g., QT, BT, and TT), may be symmetrical or asymmetrical.

The blocks (e.g., CTUs or CUs) may be grouped in various ways in a picture. As one example, a brick may refer to a rectangular region of CTU rows within a particular tile in a picture. A tile may be a rectangular region of CTUs within a particular tile column and a particular tile row in a picture. A tile column refers to a rectangular region of CTUs having a height equal to the height of the picture and a width specified by syntax elements (e.g., such as in a picture parameter set). A tile row refers to a rectangular region of CTUs having a height specified by syntax elements (e.g., such as in a picture parameter set) and a width equal to the width of the picture.

In some examples, a tile may be partitioned into multiple bricks, each of which may include one or more CTU rows within the tile. A tile that is not partitioned into multiple bricks may also be referred to as a brick. However, a brick that is a true subset of a tile may not be referred to as a tile.

The bricks in a picture may also be arranged in a slice. A slice may be an integer number of bricks of a picture that may be exclusively contained in a single network abstraction layer (NAL) unit. In some examples, a slice includes either a number of complete tiles or only a consecutive sequence of complete bricks of one tile.

Some examples of JEM and VVC also provide an affine motion compensation mode, which may be considered an inter-prediction mode. In affine motion compensation mode, video encoder <NUM> may determine two or more motion vectors that represent non-translational motion, such as zoom in or out, rotation, perspective motion, or other irregular motion types.

To perform intra-prediction, video encoder <NUM> may select an intra-prediction mode to generate the prediction block. Some examples of JEM and VVC provide sixty-seven intra-prediction modes, including various directional modes, as well as planar mode and DC mode. In general, video encoder <NUM> selects an intra-prediction mode that describes neighboring samples to a current block (e.g., a block of a CU) from which to predict samples of the current block. Such samples may generally be above, above and to the left, or to the left of the current block in the same picture as the current block, assuming video encoder <NUM> codes CTUs and CUs in raster scan order (left to right, top to bottom).

As noted above, following any transforms to produce transform coefficients, video encoder <NUM> may perform quantization of the transform coefficients. Quantization generally refers to a process in which transform coefficients are quantized to possibly reduce the amount of data used to represent the transform coefficients, providing further compression. By performing the quantization process, video encoder <NUM> may reduce the bit depth associated with some or all of the transform coefficients. For example, video encoder <NUM> may round an n-bit value down to an m-bit value during quantization, where n is greater than m. In some examples, to perform quantization, video encoder <NUM> may perform a bitwise right-shift of the value to be quantized.

Following quantization, video encoder <NUM> may scan the transform coefficients, producing a one-dimensional vector from the two-dimensional matrix including the quantized transform coefficients. The scan may be designed to place higher energy (and therefore lower frequency) transform coefficients at the front of the vector and to place lower energy (and therefore higher frequency) transform coefficients at the back of the vector. In some examples, video encoder <NUM> may utilize a predefined scan order to scan the quantized transform coefficients to produce a serialized vector, and then entropy encode the quantized transform coefficients of the vector. In other examples, video encoder <NUM> may perform an adaptive scan. After scanning the quantized transform coefficients to form the one-dimensional vector, video encoder <NUM> may entropy encode the one-dimensional vector, e.g., according to context-adaptive binary arithmetic coding (CABAC). Video encoder <NUM> may also entropy encode values for syntax elements describing metadata associated with the encoded video data for use by video decoder <NUM> in decoding the video data.

In general, video decoder <NUM> performs a reciprocal process to that performed by video encoder <NUM> to decode the encoded video data of the bitstream. For example, video decoder <NUM> may decode values for syntax elements of the bitstream using CABAC in a manner substantially similar to, albeit reciprocal to, the CABAC encoding process of video encoder <NUM>. The syntax elements may define partitioning information of a picture into CTUs, and partitioning of each CTU according to a corresponding partition structure, such as a QTBT structure, to define CUs of the CTU. The syntax elements may further define prediction and residual information for blocks (e.g., CUs) of video data.

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

At the encoder side, the joint chroma components may be derived as explained in the following. Depending on the mode (listed in the tables above), resJointC{<NUM>,<NUM>} may be generated by the encoder as follows:.

The three joint chroma coding modes described above are only supported in I slices. In P and B slices, only mode <NUM> may be supported. Hence, in P and B slices, the syntax element tu_joint_cbcr_residual_flag is only present if both chroma cbfs are <NUM>. Note that transform depth is removed in the context modeling oftu_cbf_luma and tu_cbf_cb.

In <NPL> (see also <NPL>), a sequence parameter set (SPS) level flag has been added to control enabling/disabling of joint-Cb-Cr for each video sequence (see also <NPL>). VVC Draft <NUM> incorporates these techniques and the corresponding flag is referred to as sps_joint_cber_enabled_flag.

In <NPL>"), a SPS level signaling of chroma QP mapping tables, for the derivation of chroma QP from the collocated/corresponding luma block QP, is proposed. JVET-O0650 provides flexibility to use different table for Cb, Cr, and joint-Cb-Cr, and to adapt the table based on the nature of the video content (SDR/ HDR-PQ/HDR-HLG).

The aforementioned techniques may present one or more disadvantages. In particular, in VVC Draft <NUM>, when sps_joint_cbcr_enabled_flag is <NUM>, the following occurs:.

This signaling may be redundant, which may unnecessarily decrease the coding efficiency (e.g., increase the number of bits used to represent video data at a particular quality). Relevant portions of VVC Draft <NUM> are reproduced below:.

In aspect <NUM> of <NPL>"), it was proposed to use sps_joint_cbcr_enabled_flag for the parsing of chroma QP mapping table and, pps level qp offset parameters, as shown the modification in specification text in JVET-P0426, shown below.

The solution proposed in aspect <NUM> of JVET-P0426 may present one or more disadvantages. Two specific disadvantages are discussed as follows. As a first disadvantage, currently, at the SPS level, sps_joint_cbcr_enabled_flag is parsed after the parsing of chroma QP mapping table(s). As such, the desired outcome of the proposed aspect (removing chroma QP mapping table for JCCR) may not be achieved unless the parsing order is modified. As a second disadvantage, at the PPS level, parsing of PPS syntax elements pps_joint_cbcr_qp_offset and joint_cber_qp_offset_list[ i ] depends on the SPS syntax element sps_joint_cbcr_enabled_flag. However, one of the design principles of VVC is to avoid parameter set parsing dependency. In this case, PPS parameters depend on SPS parameter which violates this design principle.

This disclosure proposes several techniques that may cure the disadvantages discussed above and/or provide other advantages. The techniques of disclosure may include two aspects, which may be used independently or in combination. In accordance with a first aspect of this disclosure, a video coder (e.g., video encoder <NUM> and/or video decoder <NUM>) may code (e.g., encoder or parse) a syntax element that indicates whether the joint coding of chroma residuals is enabled or disabled (e.g., sps_joint_cber_enabled_flag) before parsing of the chroma QP mapping table. For instance, the syntax table may be modified to adjust the parsing order of sps_joint_cber_enabled_flag.

In accordance with a second aspect of this disclosure, the video coder may code a syntax element (e.g., pps_joint_cber_qp_offset_present_flag) to control whether the QP offset for the joint Cb-Cr residuals is included in the chroma QP offset table and whether a syntax element that specifies the offset to the luma quantization parameter Qp'Y used for deriving Qp'ChCr (e.g., pps_joint_cber_qp_offset) is coded. As opposed to the approach of JVET-P0426, this approach does not have any parsing dependency.

Example changes compared to VVC Draft <NUM> are marked below in italics:.

In accordance with the techniques of this disclosure, a video coder may code a sequence parameter set (SPS) referred to by one or more pictures of video data, wherein, to code the SPS, the video coder may: code, at a first position in the SPS, a syntax element that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data referring to the SPS; and code, at a second position in the SPS that is after the first position, one or more syntax elements representing a quantization parameter (QP) mapping table; code a picture parameter set (PPS) referred to by a picture of the one or more pictures of video data, wherein, to code the PPS, the video coder may code a syntax element that indicates whether a QP offset for the joint chroma residuals is included in the chroma QP offset table and whether a syntax element that specifies an offset to the luma quantization parameter Qp'Y used for deriving Qp'CbCr is coded; and code the picture based on the SPS and the PPS.

This disclosure may generally refer to "signaling" certain information, such as syntax elements. The term "signaling" may generally refer to the communication of values for syntax elements and/or other data used to decode encoded video data. That is, video encoder <NUM> may signal values for syntax elements in the bitstream. In general, signaling refers to generating a value in the bitstream. As noted above, source device <NUM> may transport the bitstream to destination device <NUM> substantially in real time, or not in real time, such as might occur when storing syntax elements to storage device <NUM> for later retrieval by destination device <NUM>.

<FIG> are conceptual diagrams illustrating an example quadtree binary tree (QTBT) structure <NUM>, and a corresponding coding tree unit (CTU) <NUM>. The solid lines represent quadtree splitting, and dotted lines indicate binary tree splitting. In each split (i.e., non-leaf) node of the binary tree, one flag is signaled to indicate which splitting type (i.e., horizontal or vertical) is used, where <NUM> indicates horizontal splitting and <NUM> indicates vertical splitting in this example. For the quadtree splitting, there is no need to indicate the splitting type, because quadtree nodes split a block horizontally and vertically into <NUM> sub-blocks with equal size. Accordingly, video encoder <NUM> may encode, and video decoder <NUM> may decode, syntax elements (such as splitting information) for a region tree level of QTBT structure <NUM> (i.e., the solid lines) and syntax elements (such as splitting information) for a prediction tree level of QTBT structure <NUM> (i.e., the dashed lines). Video encoder <NUM> may encode, and video decoder <NUM> may decode, video data, such as prediction and transform data, for CUs represented by terminal leaf nodes of QTBT structure <NUM>.

In one example of the QTBT partitioning structure, the CTU size is set as 128x128 (luma samples and two corresponding 64x64 chroma samples), the MinQTSize is set as 16x16, the MaxBTSize is set as 64x64, the MinBTSize (for both width and height) is set as <NUM>, and the MaxBTDepth is set as <NUM>. The quadtree partitioning is applied to the CTU first to generate quad-tree leaf nodes. The quadtree leaf nodes may have a size from 16x16 (i.e., the MinQTSize) to 128x128 (i.e., the CTU size). If the leaf quadtree node is 128x128, the leaf quadtree node will not be further split by the binary tree, because the size exceeds the MaxBTSize (i.e., 64x64, in this example). Otherwise, the leaf quadtree node will be further partitioned by the binary tree. Therefore, the quadtree leaf node is also the root node for the binary tree and has the binary tree depth as <NUM>. When the binary tree depth reaches MaxBTDepth (<NUM>, in this example), no further splitting is permitted. When the binary tree node has a width equal to MinBTSize (<NUM>, in this example), it implies no further horizontal splitting is permitted. Similarly, a binary tree node having a height equal to MinBTSize implies no further vertical splitting is permitted for that binary tree node. As noted above, leaf nodes of the binary tree are referred to as CUs, and are further processed according to prediction and transform without further partitioning.

<FIG> is a block diagram illustrating an example video encoder <NUM> that may perform the techniques of this disclosure. <FIG> is provided for purposes of explanation and should not be considered limiting of the techniques as broadly exemplified and described in this disclosure. For purposes of explanation, this disclosure describes video encoder <NUM> in the context of video coding standards such as the HEVC video coding standard and the H. <NUM> video coding standard in development. However, the techniques of this disclosure are not limited to these video coding standards, and are applicable generally to video encoding and decoding.

In the example of <FIG>, video encoder <NUM> includes video data memory <NUM>, mode selection unit <NUM>, residual generation unit <NUM>, transform processing unit <NUM>, quantization unit <NUM>, inverse quantization unit <NUM>, inverse transform processing unit <NUM>, reconstruction unit <NUM>, filter unit <NUM>, decoded picture buffer (DPB) <NUM>, and entropy encoding unit <NUM>. Any or all of video data memory <NUM>, mode selection unit <NUM>, residual generation unit <NUM>, transform processing unit <NUM>, quantization unit <NUM>, inverse quantization unit <NUM>, inverse transform processing unit <NUM>, reconstruction unit <NUM>, filter unit <NUM>, DPB <NUM>, and entropy encoding unit <NUM> may be implemented in one or more processors or in processing circuitry. For instance, the units of video encoder <NUM> may be implemented as one or more circuits or logic elements as part of hardware circuitry, or as part of a processor, ASIC, of FPGA. Moreover, video encoder <NUM> may include additional or alternative processors or processing circuitry to perform these and other functions.

The various units of <FIG> are illustrated to assist with understanding the operations performed by video encoder <NUM>. The units may be implemented as fixed-function circuits, programmable circuits, or a combination thereof. Fixed-function circuits refer to circuits that provide particular functionality, and are preset on the operations that can be performed. Programmable circuits refer to circuits that can be programmed to perform various tasks, and provide flexible functionality in the operations that can be performed. For instance, programmable circuits may execute software or firmware that cause the programmable circuits to operate in the manner defined by instructions of the software or firmware. Fixed-function circuits may execute software instructions (e.g., to receive parameters or output parameters), but the types of operations that the fixed-function circuits perform are generally immutable. In some examples, one or more of the units may be distinct circuit blocks (fixed-function or programmable), and in some examples, one or more of the units may be integrated circuits.

Video encoder <NUM> may include arithmetic logic units (ALUs), elementary function units (EFUs), digital circuits, analog circuits, and/or programmable cores, formed from programmable circuits. In examples where the operations of video encoder <NUM> are performed using software executed by the programmable circuits, memory <NUM> (<FIG>) may store the instructions (e.g., object code) of the software that video encoder <NUM> receives and executes, or another memory within video encoder <NUM> (not shown) may store such instructions.

Mode selection unit <NUM> includes a motion estimation unit <NUM>, motion compensation unit <NUM>, and an intra-prediction unit <NUM>. Mode selection unit <NUM> may include additional functional units to perform video prediction in accordance with other prediction modes. As examples, mode selection unit <NUM> may include a palette unit, an intra-block copy unit (which may be part of motion estimation unit <NUM> and/or motion compensation unit <NUM>), an affine unit, a linear model (LM) unit, or the like.

Video encoder <NUM> may partition a picture retrieved from video data memory <NUM> into a series of CTUs, and encapsulate one or more CTUs within a slice. Mode selection unit <NUM> may partition a CTU of the picture in accordance with a tree structure, such as the QTBT structure or the quad-tree structure of HEVC described above. As described above, video encoder <NUM> may form one or more CUs from partitioning a CTU according to the tree structure. Such a CU may also be referred to generally as a "video block" or "block.

Motion estimation unit <NUM> may form one or more motion vectors (MVs) that defines the positions of the reference blocks in the reference pictures relative to the position of the current block in a current picture. Motion estimation unit <NUM> may then provide the motion vectors to motion compensation unit <NUM>. For example, for uni-directional inter-prediction, motion estimation unit <NUM> may provide a single motion vector, whereas for bi-directional inter-prediction, motion estimation unit <NUM> may provide two motion vectors. Motion compensation unit <NUM> may then generate a prediction block using the motion vectors. For example, motion compensation unit <NUM> may retrieve data of the reference block using the motion vector. As another example, if the motion vector has fractional sample precision, motion compensation unit <NUM> may interpolate values for the prediction block according to one or more interpolation filters. Moreover, for bi-directional inter-prediction, motion compensation unit <NUM> may retrieve data for two reference blocks identified by respective motion vectors and combine the retrieved data, e.g., through sample-by-sample averaging or weighted averaging.

Mode selection unit <NUM> provides the prediction block to residual generation unit <NUM>. Residual generation unit <NUM> receives a raw, unencoded version of the current block from video data memory <NUM> and the prediction block from mode selection unit <NUM>. Residual generation unit <NUM> calculates sample-by-sample differences between the current block and the prediction block. The resulting sample-by-sample differences define a residual block for the current block. In some examples, residual generation unit <NUM> may also determine differences between sample values in the residual block to generate a residual block using residual differential pulse code modulation (RDPCM). In some examples, residual generation unit <NUM> may be formed using one or more subtractor circuits that perform binary subtraction.

In examples where mode selection unit <NUM> does not further partition a CU into PUs, each CU may be associated with a luma coding block and corresponding chroma coding blocks. As above, the size of a CU may refer to the size of the luma coding block of the CU. The video encoder <NUM> and video decoder <NUM> may support CU sizes of 2Nx2N, 2NxN, or Nx2N.

For other video coding techniques such as an intra-block copy mode coding, an affine-mode coding, and linear model (LM) mode coding, as few examples, mode selection unit <NUM>, via respective units associated with the coding techniques, generates a prediction block for the current block being encoded. In some examples, such as palette mode coding, mode selection unit <NUM> may not generate a prediction block, and instead generate syntax elements that indicate the manner in which to reconstruct the block based on a selected palette. In such modes, mode selection unit <NUM> may provide these syntax elements to entropy encoding unit <NUM> to be encoded.

Quantization unit <NUM> may quantize the transform coefficients in a transform coefficient block, to produce a quantized transform coefficient block. Quantization unit <NUM> may quantize transform coefficients of a transform coefficient block according to a quantization parameter (QP) value associated with the current block. Video encoder <NUM> (e.g., via mode selection unit <NUM>) may adjust the degree of quantization applied to the transform coefficient blocks associated with the current block by adjusting the QP value associated with the CU. Quantization may introduce loss of information, and thus, quantized transform coefficients may have lower precision than the original transform coefficients produced by transform processing unit <NUM>.

Filter unit <NUM> may perform one or more filter operations on reconstructed blocks. For example, filter unit <NUM> may perform deblocking operations to reduce blockiness artifacts along edges of CUs. Operations of filter unit <NUM> may be skipped, in some examples.

Video encoder <NUM> stores reconstructed blocks in DPB <NUM>. For instance, in examples where operations of filter unit <NUM> are not needed, reconstruction unit <NUM> may store reconstructed blocks to DPB <NUM>. In examples where operations of filter unit <NUM> are needed, filter unit <NUM> may store the filtered reconstructed blocks to DPB <NUM>. Motion estimation unit <NUM> and motion compensation unit <NUM> may retrieve a reference picture from DPB <NUM>, formed from the reconstructed (and potentially filtered) blocks, to inter-predict blocks of subsequently encoded pictures. In addition, intra-prediction unit <NUM> may use reconstructed blocks in DPB <NUM> of a current picture to intra-predict other blocks in the current picture.

In some examples, operations performed with respect to a luma coding block need not be repeated for the chroma coding blocks. As one example, operations to identify a motion vector (MV) and reference picture for a luma coding block need not be repeated for identifying a MV and reference picture for the chroma blocks. Rather, the MV for the luma coding block may be scaled to determine the MV for the chroma blocks, and the reference picture may be the same. As another example, the intra-prediction process may be the same for the luma coding block and the chroma coding blocks.

Video encoder <NUM> represents an example of a device configured to encode video data including a memory configured to store video data, and one or more processing units implemented in circuitry and configured to encode a sequence parameter set (SPS) referred to by one or more pictures of video data, wherein, to encode the SPS, the video encoder may: encode, at a first position in the SPS, a syntax element that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data referring to the SPS; and encode, at a second position in the SPS that is after the first position, one or more syntax elements representing a quantization parameter (QP) mapping table; encode a picture parameter set (PPS) referred to by a picture of the one or more pictures of video data, wherein, to encode the PPS, the video encoder may encode a syntax element that indicates whether a QP offset for the joint chroma residuals is included in the chroma QP offset table and whether a syntax element that specifies an offset to the luma quantization parameter Qp'Y used for deriving Qp'CbCr is encoded; and encode the picture based on the SPS and the PPS.

<FIG> is a block diagram illustrating an example video decoder <NUM> that may perform the techniques of this disclosure. <FIG> is provided for purposes of explanation and is not limiting on the techniques as broadly exemplified and described in this disclosure. For purposes of explanation, this disclosure describes video decoder <NUM> according to the techniques of JEM, VVC, and HEVC. However, the techniques of this disclosure may be performed by video coding devices that are configured to other video coding standards.

In the example of <FIG>, video decoder <NUM> includes coded picture buffer (CPB) memory <NUM>, entropy decoding unit <NUM>, prediction processing unit <NUM>, inverse quantization unit <NUM>, inverse transform processing unit <NUM>, reconstruction unit <NUM>, filter unit <NUM>, and decoded picture buffer (DPB) <NUM>. Any or all of CPB memory <NUM>, entropy decoding unit <NUM>, prediction processing unit <NUM>, inverse quantization unit <NUM>, inverse transform processing unit <NUM>, reconstruction unit <NUM>, filter unit <NUM>, and DPB <NUM> may be implemented in one or more processors or in processing circuitry. For instance, the units of video decoder <NUM> may be implemented as one or more circuits or logic elements as part of hardware circuitry, or as part of a processor, ASIC, of FPGA. Moreover, video decoder <NUM> may include additional or alternative processors or processing circuitry to perform these and other functions.

Prediction processing unit <NUM> includes motion compensation unit <NUM> and intra-prediction unit <NUM>. Prediction processing unit <NUM> may include additional units to perform prediction in accordance with other prediction modes. As examples, prediction processing unit <NUM> may include a palette unit, an intra-block copy unit (which may form part of motion compensation unit <NUM>), an affine unit, a linear model (LM) unit, or the like. In other examples, video decoder <NUM> may include more, fewer, or different functional components.

CPB memory <NUM> may store video data, such as an encoded video bitstream, to be decoded by the components of video decoder <NUM>. The video data stored in CPB memory <NUM> may be obtained, for example, from computer-readable medium <NUM> (<FIG>). CPB memory <NUM> may include a CPB that stores encoded video data (e.g., syntax elements) from an encoded video bitstream. Also, CPB memory <NUM> may store video data other than syntax elements of a coded picture, such as temporary data representing outputs from the various units of video decoder <NUM>. DPB <NUM> generally stores decoded pictures, which video decoder <NUM> may output and/or use as reference video data when decoding subsequent data or pictures of the encoded video bitstream. CPB memory <NUM> and DPB <NUM> may be formed by any of a variety of memory devices, such as DRAM, including SDRAM, MRAM, RRAM, or other types of memory devices. CPB memory <NUM> and DPB <NUM> may be provided by the same memory device or separate memory devices. In various examples, CPB memory <NUM> may be on-chip with other components of video decoder <NUM>, or off-chip relative to those components.

Additionally or alternatively, in some examples, video decoder <NUM> may retrieve coded video data from memory <NUM> (<FIG>). That is, memory <NUM> may store data as discussed above with CPB memory <NUM>. Likewise, memory <NUM> may store instructions to be executed by video decoder <NUM>, when some or all of the functionality of video decoder <NUM> is implemented in software to be executed by processing circuitry of video decoder <NUM>.

The various units shown in <FIG> are illustrated to assist with understanding the operations performed by video decoder <NUM>. The units may be implemented as fixed-function circuits, programmable circuits, or a combination thereof. Similar to <FIG>, fixed-function circuits refer to circuits that provide particular functionality, and are preset on the operations that can be performed. Programmable circuits refer to circuits that can be programmed to perform various tasks, and provide flexible functionality in the operations that can be performed. For instance, programmable circuits may execute software or firmware that cause the programmable circuits to operate in the manner defined by instructions of the software or firmware. Fixed-function circuits may execute software instructions (e.g., to receive parameters or output parameters), but the types of operations that the fixed-function circuits perform are generally immutable. In some examples, one or more of the units may be distinct circuit blocks (fixed-function or programmable), and in some examples, one or more of the units may be integrated circuits.

After inverse quantization unit <NUM> forms the transform coefficient block, inverse transform processing unit <NUM> may apply one or more inverse transforms to the transform coefficient block to generate a residual block associated with the current block. For example, inverse transform processing unit <NUM> may apply an inverse DCT, an inverse integer transform, an inverse Karhunen-Loeve transform (KLT), an inverse rotational transform, an inverse directional transform, or another inverse transform to the transform coefficient block.

Filter unit <NUM> may perform one or more filter operations on reconstructed blocks. For example, filter unit <NUM> may perform deblocking operations to reduce blockiness artifacts along edges of the reconstructed blocks. Operations of filter unit <NUM> are not necessarily performed in all examples.

Video decoder <NUM> may store the reconstructed blocks in DPB <NUM>. For instance, in examples where operations of filter unit <NUM> are not performed, reconstruction unit <NUM> may store reconstructed blocks to DPB <NUM>. In examples where operations of filter unit <NUM> are performed, filter unit <NUM> may store the filtered reconstructed blocks to DPB <NUM>. As discussed above, DPB <NUM> may provide reference information, such as samples of a current picture for intra-prediction and previously decoded pictures for subsequent motion compensation, to prediction processing unit <NUM>. Moreover, video decoder <NUM> may output decoded pictures (e.g., decoded video) from DPB <NUM> for subsequent presentation on a display device, such as display device <NUM> of <FIG>.

In this manner, video decoder <NUM> represents an example of a video decoding device including a memory configured to store video data, and one or more processing units implemented in circuitry and configured to decode a sequence parameter set (SPS) referred to by one or more pictures of video data, wherein, to decode the SPS, the video decoder may: decode, at a first position in the SPS, a syntax element that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data referring to the SPS; and decode, at a second position in the SPS that is after the first position, one or more syntax elements representing a quantization parameter (QP) mapping table; decode a picture parameter set (PPS) referred to by a picture of the one or more pictures of video data, wherein, to decode the PPS, the video decoder may decode a syntax element that indicates whether a QP offset for the joint chroma residuals is included in the chroma QP offset table and whether a syntax element that specifies an offset to the luma quantization parameter Qp'Y used for deriving Qp'CbCr is signalled; and decode the picture based on the SPS and the PPS.

<FIG> is a flowchart illustrating an example method for encoding a current block. The current block may comprise a current CU. Although described with respect to video encoder <NUM> (<FIG> and <FIG>), it should be understood that other devices may be configured to perform a method similar to that of <FIG>.

In this example, video encoder <NUM> initially predicts the current block (<NUM>). For example, video encoder <NUM> may form a prediction block for the current block. Video encoder <NUM> may then calculate a residual block for the current block (<NUM>). To calculate the residual block, video encoder <NUM> may calculate a difference between the original, unencoded block and the prediction block for the current block. Video encoder <NUM> may then transform and quantize coefficients of the residual block (<NUM>). Next, video encoder <NUM> may scan the quantized transform coefficients of the residual block (<NUM>). During the scan, or following the scan, video encoder <NUM> may entropy encode the transform coefficients (<NUM>). For example, video encoder <NUM> may encode the transform coefficients using CAVLC or CABAC. Video encoder <NUM> may then output the entropy encoded data of the block (<NUM>).

<FIG> is a flowchart illustrating an example method for decoding a current block of video data. The current block may comprise a current CU. Although described with respect to video decoder <NUM> (<FIG> and <FIG>), it should be understood that other devices may be configured to perform a method similar to that of <FIG>.

Video decoder <NUM> may receive entropy encoded data for the current block, such as entropy encoded prediction information and entropy encoded data for coefficients of a residual block corresponding to the current block (<NUM>). Video decoder <NUM> may entropy decode the entropy encoded data to determine prediction information for the current block and to reproduce coefficients of the residual block (<NUM>). Video decoder <NUM> may predict the current block (<NUM>), e.g., using an intra- or inter-prediction mode as indicated by the prediction information for the current block, to calculate a prediction block for the current block. Video decoder <NUM> may then inverse scan the reproduced coefficients (<NUM>), to create a block of quantized transform coefficients. Video decoder <NUM> may then inverse quantize and inverse transform the transform coefficients to produce a residual block (<NUM>). Video decoder <NUM> may ultimately decode the current block by combining the prediction block and the residual block (<NUM>).

<FIG> is a flowchart illustrating an example method for coding a current block of video data. The current block may comprise a current CU. Although described with respect to video decoder <NUM> (<FIG> and <FIG>), it should be understood that other devices may be configured to perform a method similar to that of <FIG>.

Video decoder <NUM> may decode, from an encoded video bitstream, a sequence parameter set (SPS) referred to by one or more pictures of video data. For instance, entropy decoding unit <NUM> may parse, at a first position in the SPS, a syntax element that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data referring to the SPS (<NUM>); and parse, at a second position in the SPS that is after the first position, one or more syntax elements representing quantization parameter (QP) mapping tables (<NUM>). In some examples, the syntax element that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data referring to the SPS may include a sps_joint_cbcr_enabled_flag syntax element. In some examples, the one or more syntax elements representing a quantization parameter (QP) mapping table may include one or more num_points_in_qp_table_minus1[ i ] syntax elements, one or more delta_qp_in_val_minus1[ i ][ j ] syntax elements, and one or more delta_qp_out_val[ I ][ j ] syntax elements. As discussed above, by parsing the a syntax element that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data referring to the SPS before the one or more syntax elements representing quantization parameter (QP) mapping tables, video decoder <NUM> may avoid decoding syntax elements representing quantization parameter (QP) mapping tables for joint Cb-Cr mapping table where joint coding of chroma residuals is disabled.

Video decoder <NUM> may decode, from the encoded video bitstream, a picture parameter set (PPS) referred to by a picture of the one or more pictures of video data. For instance, entropy decoding unit <NUM> may parse, from the PPS, a syntax element that indicates whether syntax elements related to joint coding of chroma residuals are present in the PPS (<NUM>). The syntax element that indicates whether syntax elements related to joint coding of chroma residuals are present in the PPS may be a syntax element that indicates whether a QP offset for jointly coded chroma residuals is included in a chroma QP offset table and whether a syntax element that specifies an offset to a luma quantization parameter Qp'Y used for deriving Qp'CbCr is coded. In some examples, the syntax element that indicates whether a QP offset for the jointly coded chroma residuals is included in the chroma QP offset table and whether the syntax element that specifies the offset to the luma quantization parameter Qp'Y used for deriving Qp'CbCr is coded may be a pps_joint_cber_qp_offset_present_flag syntax element.

In some examples, to decode the PPS, entropy decoding unit <NUM> may parse the syntax elements related to joint coding of chroma residuals based on the value of the parsed syntax element (e.g., based on a value of pps_joint_cbcr_qp_offset_present_ flag). For instance, pps_joint_cbcr_qp_offset_present_ flag indicates that pps_joint_cber_qp_offset and joint_cber_qp_offset_list[ i ] are present, entropy decoding unit <NUM> may parse, from the PPS, the pps_joint_cbcr_qp_offset and joint_cbcr_qp_offset_list[ i ] syntax elements.

Video decoder <NUM> may decode the picture based on the SPS and the PPS (<NUM>). For instance, entropy decoding unit <NUM> may selectively perform joint chroma residual coding based on values of the syntax elements of the SPS and PPS. In some examples, to decode the picture based on the SPS and the PPS, video decoder <NUM> may decode the picture based on the QP mapping table specified by the SPS.

Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Accordingly, the terms "processor" and "processing circuitry," as used herein may refer to any of the foregoing structures or any other structure suitable for implementation of the techniques described herein.

Claim 1:
A method of decoding video data, the method comprising:
decoding, from an encoded video bitstream, a sequence parameter set, SPS, referred to by one or more pictures of video data, wherein decoding the SPS comprises:
parsing (<NUM>), at a first position in the SPS, a syntax element that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of the video data referring to the SPS; and
parsing (<NUM>), at a second position in the SPS that is after the first position and based on a value of the syntax element that indicates whether joint coding of chroma residuals is enabled or disabled, one or more syntax elements representing a quantization parameter, QP, mapping table;
decoding, from the encoded video bitstream, a picture parameter set, PPS, referred to by a picture of the one or more pictures of video data, wherein decoding the PPS comprises:
parsing (<NUM>) a syntax element that indicates whether a QP offset for jointly coded chroma residuals is included in a chroma QP offset table and whether a syntax element that specifies an offset to a luma quantization parameter Qp'Y used for deriving Qp'CbCr is coded; and
decoding (<NUM>) the picture based on the SPS and the PPS.