Single hue palette mode for video coding

Abstract

A method of decoding video data includes determining that a current block of video data is coded in a palette mode, determining, between a single tree partitioning or a dual tree partitioning, that the current block is coded with the single tree partitioning enabled, determining that the current block is coded in a monochrome format, determining, when the current block is coded with the single tree partitioning enabled and when the current block is coded in the monochrome format, that a number of color components used for palette mode decoding of the current block is equal to one, and palette mode decoding the current block based on the determined number of color components used for palette mode decoding of the current block being equal to one.

Description

[0001] This application claims the benefit of U.S. Application No. 17 / 132,836, filed December 23, 2020, and U.S. Provisional Application No. 62 / 953,713, filed December 26, 2019, the entire contents of which are incorporated herein by reference. U.S. Application No. 17 / 132,836 claims the benefit of U.S. Provisional Application No. 62 / 953,713, filed December 26, 2019. TECHNICAL FIELD

[0002] The present disclosure relates to video encoding and video decoding. BACKGROUND

[0003] Digital video capabilities can be incorporated into a wide range of devices, including digital televisions, digital direct broadcast systems, wireless broadcast systems, personal digital assistants (PDAs), laptop or desktop computers, tablet computers, e-book readers, digital cameras, digital recording devices, digital media players, video gaming devices, video game consoles, cellular or satellite radio telephones, so-called “smart phones,” video teleconferencing devices, video streaming devices, and the like. Digital video devices implement video coding techniques, such as those described in the standards defined by MPEG-2, MPEG-4, ITU-T H.263, ITU-T H.264 / MPEG-4, Part 10, Advanced Video Coding (AVC), ITU-T H.265 / High Efficiency Video Coding (HEVC), and extensions of such standards. The video devices can more efficiently send, receive, encode, decode, and / or store digital video information by implementing such video coding techniques.

[0004] Video coding techniques include spatial (intra-picture) prediction and / or temporal (inter-picture) prediction to reduce or remove redundancy inherent in the video sequence. For block-based video coding, a video slice (e.g., a video picture or a portion of a video picture) can be partitioned into video blocks, which can also be referred to as coding tree units (CTUs), coding units (CUs), and / or coding nodes. Video blocks in the intra-coded (I) slices of a picture are coded using spatial prediction with respect to reference samples in neighboring blocks in the same picture. Video blocks in the inter-coded (P or B) slices of a picture can be coded using either spatial prediction with respect to reference samples in neighboring blocks in the same picture or temporal prediction with respect to reference samples in other reference pictures. Pictures can be referred to as frames, and reference pictures can be referred to as reference frames. SUMMARY

[0005] In general, this disclosure describes techniques for enabling palette mode coding for monochrome content and / or enabling palette mode coding when separate color plane coding is used. Example techniques can be applicable to video coding standards such as the Versatile Video Coding (VVC) standard, but can be applicable to other video coding standards and generally to video coding techniques, including both standard-based and non-standard based video coding techniques.

[0006] As described in more detail, in some examples, an image can be partitioned according to a dual tree partition or a single tree partition. In a dual tree partition, there can be different partitions of a luma component of the image and a chroma component of the image. In a single tree partition, the luma component and the chroma component of the image are partitioned in the same way.

[0007] This disclosure describes examples that utilize both a partition (e.g., a single tree partition or a dual tree partition) and a color format (e.g., whether it is a monochrome format) as criteria to determine a number of color components for palette mode coding. In this way, when a video decoder is performing operations defined by a palette mode coding syntax structure, the video decoder can correctly determine a number of color components for palette mode coding of a current block.

[0008] In one example, this disclosure describes a method of decoding video data, the method comprising: determining that a current block of the video data is coded in a palette mode; determining, between a single tree partition or a dual tree partition, that the current block is coded with the single tree partition enabled; determining that the current block is coded in a monochrome format; determining that a number of color components for palette mode decoding of the current block is equal to one when the current block is coded with the single tree partition enabled and when the current block is coded in the monochrome format; and palette mode decoding the current block based on the determined number of color components for palette mode decoding of the current block being equal to one.

[0009] In one example, this disclosure describes an apparatus for coding video data, the apparatus comprising: a memory configured to store the video data; and processing circuitry coupled to the memory and configured to: determine that a current block of the video data is coded in a palette mode; determine, between a single tree partition or a dual tree partition, that the current block is coded with the single tree partition enabled; determine that the current block is coded in a monochrome format; determine that a number of color components for palette mode decoding of the current block is equal to one when the current block is coded with the single tree partition enabled and when the current block is coded in the monochrome format; and palette mode decode the current block based on the determined number of color components for palette mode decoding of the current block being equal to one.

[0010] In one example, this disclosure describes a computer-readable storage medium having instructions stored thereon that when executed cause one or more processors to determine that a current block of video data is coded in a palette mode; determine, between a single tree partitioning or a dual tree partitioning, that the current block is coded with the single tree partitioning enabled; determine that the current block is coded in a monochrome format; when the current block is coded with the single tree partitioning enabled and when the current block is coded in the monochrome format, determine that a number of color components used for palette mode decoding of the current block is equal to one; and based on the determined number of color components used for palette mode decoding of the current block being equal to one, decode the current block in the palette mode.

[0011] In one example, this disclosure describes a device for decoding video data, the device comprising: means for determining that a current block of video data is coded in a palette mode; means for determining, between a single tree partitioning or a dual tree partitioning, that the current block is coded with the single tree partitioning enabled; means for determining that the current block is coded in a monochrome format; when the current block is coded with the single tree partitioning enabled and when the current block is coded in the monochrome format, means for determining that a number of color components used for palette mode decoding of the current block is equal to one; and means for decoding the current block in the palette mode based on the determined number of color components used for palette mode decoding of the current block being equal to one.

[0012] The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a block diagram illustrating an example video encoding and decoding system that can perform the techniques of this disclosure.

[0014] Figure 2A and Figure 2B is a conceptual diagram illustrating an example quad-tree binary-tree (QTBT) structure and a corresponding coding tree unit (CTU).

[0015] Figure 3 is a block diagram illustrating an example video encoder that can perform the techniques of this disclosure.

[0016] Figure 4 is a block diagram illustrating an example video decoder that can perform the techniques of this disclosure.

[0017] Figure 5 is a flowchart illustrating an example of coding video data.

[0018] Figure 6 is a flowchart illustrating an example technique described in the present disclosure. DETAILED DESCRIPTION

[0019] In video coding, an example coding mode is palette mode coding. In palette mode coding, a video encoder signals a palette mode table that includes sample values referenced by indices with respect to the palette mode table, and a video decoder constructs the palette mode table based on the signaled sample values. For a sample in a current block, the video encoder signals an index with respect to the palette mode table, and the video decoder determines a sample value for the sample in the current block based on a sample value in the palette mode table associated with the index with respect to the palette mode table. Palette mode coding can be available regardless of color format. For example, palette mode coding can be available in the presence of both luma and chroma components or in the presence of only luma components (e.g., monochrome). Monochrome refers to a color format indicating that only luma components are present for a block and no chroma components are present for the block, sometimes referred to as 4:0:0 color format.

[0020] As one non-limiting example, palette mode coding can be beneficial in screen content coding. For example, if a string of samples in a current block has the same value or has the same value as a neighboring sample, a video encoder can signal a run length indicating a number of samples in the string instead of signaling an index per sample. A video decoder can determine sample values for the samples in the string of samples based on the neighboring sample without needing to process indices with respect to the palette mode table for the samples in the string of samples. In some examples, a sample value for a sample can not be present in the palette mode table (referred to as an escape sample or escape pixel), and in such examples, the video encoder can signal an actual sample value for such escape samples.

[0021] In video coding, there can also be partition tree types. A partition tree type indicates a manner in which an image is partitioned into blocks. Examples of partition types include dual tree partitioning and single tree partitioning. In single tree partitioning, both luma and chroma components of an image are partitioned using the same tree structure, and thus, the luma and chroma components are partitioned in the same way. In dual tree partitioning, the luma and chroma components can be partitioned using different tree structures, and thus, the luma and chroma components can be partitioned in different ways.

[0022] The present disclosure describes example techniques in which both the partition tree type and the color format (e.g., whether monochrome) are factors that influence the number of color components used for palette mode coding (e.g., encoding or decoding) of a current block. The number of color components used for palette mode coding of a current block can refer to the number of color components in a palette mode table. Accordingly, the number of color components used for palette mode coding can be considered as the number of color components used for palette mode coding. Examples of color components include a luma component and a chroma component.

[0023] For example, when a first block is coded with single tree partitioning enabled and when the first block is coded in a monochrome format, a video coder (e.g., a video encoder or a video decoder) can determine that the number of color components used for palette mode coding of the first block is equal to one. For example, the video decoder can decode the first block based on a palette mode table that is for a luma component only (e.g., the palette mode table includes sample values for a luma component only). However, when a second block is coded with single tree partitioning enabled and when the second block is not coded in a monochrome format, the video coder can determine that the number of color components used for palette mode coding of the second block is equal to three. For example, the video decoder can decode the second block based on a palette mode table that includes both a luma component and a chroma component (e.g., the palette mode table includes sample values for both a luma component and a chroma component).

[0024] As described in more detail, as part of performing operations defined in a palette mode coding syntax structure, a video decoder can determine the number of color components used for palette mode coding. By utilizing information indicating a partition tree type and information indicating a color format (e.g., monochrome or non-monochrome), as part of performing operations defined in a palette mode coding syntax structure, a video decoder can appropriately determine the number of color components used for palette mode coding.

[0025] For example, some other techniques determine whether to enable single-tree partitioning or dual-tree partitioning, and if single-tree partitioning is enabled, determine that the number of color components used for palette mode decoding is three (e.g., the palette mode table includes sample values ​​for both the luma and chroma components). However, such other techniques fail to account for the fact that if the color format is monochrome, the number of color components used for palette mode decoding should not be three, but only one, because monochrome formats only include the luma component. In the example techniques described in this disclosure, because both the partitioning tree type and the color format (e.g., monochrome or non-monochrome) are factors in determining the number of color components used for palette mode decoding, the video decoder can correctly determine the number of color components used for palette mode decoding.

[0026] Figure 1 This is a block diagram illustrating an example video encoding and decoding system 100 capable of performing the techniques of this disclosure. The techniques of this disclosure are generally directed to decoding (encoding and / or decoding) video data. Typically, video data includes any data used for processing video. Therefore, video data can include raw, unencoded video, encoded video, decoded (e.g., reconstructed) video, and video metadata (such as signaling data).

[0027] As in Figure 1 As illustrated in this example, system 100 includes a source device 102 that provides encoded video data to be decoded and displayed by a target device 116. Specifically, source device 102 provides the video data to target device 116 via a computer-readable medium 110. Source device 102 and target device 116 can include any of a wide variety of devices, including desktop computers, laptop computers, tablet computers, set-top boxes, mobile phones (such as smartphones), televisions, cameras, display devices, digital media players, video game consoles, video streaming devices, etc. In some cases, source device 102 and target device 116 may be equipped for wireless communication and therefore may be referred to as wireless communication devices.

[0028] exist Figure 1In the example, source device 102 includes a video source 104, memory 106, video encoder 200, and output interface 108. Target device 116 includes an input interface 122, video decoder 300, memory 120, and display device 118. According to this disclosure, the video encoder 200 of source device 102 and the video decoder 300 of target device 116 can be configured to apply techniques for enabling palette modes for monochrome content and / or when using separate color plane decoding. Therefore, source device 102 represents an example of a video encoding device, and target device 116 represents an example of a video decoding device. In other examples, the source device and target device may include other components or arrangements. For example, source device 102 may receive video data from an external video source (such as an external camera). Similarly, target device 116 may interface with an external display device, rather than including an integrated display device.

[0029] As in Figure 1 The system 100 shown is merely an example. Typically, any digital video encoding and / or decoding device can perform techniques for enabling palette modes when decoding monochrome content and / or using separate color planes. Source device 102 and target device 116 are merely examples of such decoding devices, where source device 102 generates decoded video data for transmission to target device 116. This disclosure refers to a “decoding” device as a device that performs the decoding (e.g., encoding and / or decoding) of data. Therefore, video encoder 200 and video decoder 300 represent examples of decoding devices, specifically, video encoder and video decoder, respectively. In some examples, source device 102 and target device 116 may operate in a substantially symmetrical manner, such that each of source device 102 and target device 116 includes video encoding and decoding components. Thus, system 100 can support one-way or two-way video transmission between source device 102 and target device 116, for example, for video streaming, video playback, video broadcasting, or video telephony.

[0030] In general, video source 104 represents a source of video data (i.e., raw, uncoded video data) and provides a sequential series of pictures (also referred to as “frames”) of the video data to video encoder 200, which encodes data for the pictures. Video source 104 of source device 102 can 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 104 can generate computer graphics-based data as the source video, or a combination of live, archived, and computer-generated video. In each case, video encoder 200 encodes the captured, pre-captured, or computer-generated video data. Video encoder 200 can rearrange the pictures from the received order (sometimes referred to as “display order”) into the coding order for coding. Video encoder 200 can generate a bitstream including encoded video data. Source device 102 can then output the encoded video data via output interface 108 onto computer- readable medium 110 for reception and / or retrieval by, for example, input interface 122 of destination device 116.

[0031] Memory 106 of source device 102 and memory 120 of destination device 116 represent general purpose memories. In some examples, memories 106 and 120 can store raw video data, e.g., raw video from video source 104 and raw decoded video data from video decoder 300. Additionally or alternatively, memories 106 and 120 can store software instructions executable by, for example, video encoder 200 and video decoder 300, respectively. While memories 106 and 120 are shown as separate from video encoder 200 and video decoder 300 in this example, it should be understood that video encoder 200 and video decoder 300 can also include internal memories for similar or equivalent purposes. Furthermore, memories 106 and 120 can store encoded video data that is output, for example, from video encoder 200 and input to video decoder 300. In some examples, portions of memories 106 and 120 can be allocated as one or more video buffers, e.g., to store raw, decoded, and / or encoded video data.

[0032] Computer-readable medium 110 can represent any type of medium or device capable of transporting the encoded video data from source device 102 to target device 116. In one example, computer-readable medium 110 represents a communication medium to enable source device 102 to transmit directly to target device 116 encoded video data in real-time, e.g., via a radio frequency network or computer-based network. Output interface 108 can modulate a transmission signal including the encoded video data, and input interface 122 can demodulate the received transmission signal, according to a communication standard, such as a wireless communication protocol. The communication medium can comprise any wireless or wired communication medium, such as a radio frequency (RF) spectrum or one or more physical transmission lines. The communication medium can 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 can include routers, switches, base stations, or any other equipment that can be useful to facilitate communication from source device 102 to target device 116.

[0033] In some examples, source device 102 can output encoded data from output interface 108 to storage device 112. Similarly, target device 116 can access encoded data from storage device 112 via input interface 122. Storage device 112 can 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.

[0034] In some examples, source device 102 can output encoded video data to file server 114, which can store the encoded video data generated by source device 102. Target device 116 can access stored video data from file server 114 via streaming or download.

[0035] The file server 114 can be any type of server device capable of storing encoded video data and transmitting that encoded video data to the destination device 116. The file server 114 can represent a web server (e.g., for a website), a server configured to provide file transfer protocol services (such as File Transfer Protocol (FTP) or File Delivery over Unidirectional Transport (FLUTE) protocol), a content delivery network (CDN) device, a hypertext transfer protocol (HTTP) server, a multimedia broadcast multicast service (MBMS) or enhanced MBMS (eMBMS) server, and / or a network attached storage (NAS) device. Additionally or alternatively, the file server 114 can implement one or more HTTP streaming protocols, such as Dynamic Adaptive Streaming over HTTP (DASH), HTTP Live Streaming (HLS), Real Time Streaming Protocol (RTSP), HTTP Dynamic Streaming, and / or the like.

[0036] The destination device 116 can access encoded video data from the file server 114 through any standard data connection, including an Internet connection. This can include a wireless channel (e.g., a Wi-Fi connection), a wired connection (e.g., digital subscriber line (DSL), a cable modem, or the like), or a combination of both, suitable for accessing encoded video data stored on the file server 114. The input interface 122 can be configured to operate according to any one or more of the various protocols discussed above for retrieving or receiving media data from the file server 114, or other such protocols for retrieving media data.

[0037] The output interface 108 and the input interface 122 can represent wireless transmitters / receivers, modems, wired networking components (e.g., Ethernet cards), wireless communication components operating according to any of a variety of IEEE 802.11 standards, or other physical components. In examples where the output interface 108 and the input interface 122 include wireless components, the output interface 108 and the input interface 122 can be configured to transmit data (such as encoded video data) according to a cellular communication standard, such as 4G, 4G-LTE (Long-Term Evolution), LTE Advanced, 5G, or the like. In some examples where the output interface 108 includes a wireless transmitter, the output interface 108 and the input interface 122 can be configured to transmit data according to other wireless standards such as IEEE 802.11 specifications (e.g., WiFi), IEEE 802.15 specifications (e.g., ZigBee TMData (such as encoded video data) can be transmitted using standards such as Bluetooth. In some examples, source device 102 and / or target device 116 may include corresponding system-on-chip (SoC) devices. For example, source device 102 may include an SoC device to perform functions believed to be performed by video encoder 200 and / or output interface 108, and target device 116 may include an SoC device to perform functions believed to be performed by video decoder 300 and / or input interface 122.

[0038] The technology disclosed herein can be applied to video decoding to support any application in a variety of multimedia applications, such as wireless television broadcasting, cable television transmission, satellite television transmission, internet streaming video transmission (such as HTTP-based Dynamic Adaptive Streaming (DASH)), digital video encoded onto data storage media, decoding digital video stored on data storage media, or other applications.

[0039] The input interface 122 of the target device 116 receives an encoded video bitstream from a computer-readable medium 110 (e.g., a communication medium, storage device 112, file server 114, etc.). The encoded video bitstream may include signaling information defined by the video encoder 200 and also used by the video decoder 300, such as syntax elements having values ​​describing the characteristics and / or processing of video blocks or other decoded units (e.g., slices, images, image groups, sequences, etc.). The display device 118 displays a decoded image of the decoded video data to the user. The display device 118 may represent any of a variety of display devices, such as a cathode ray tube (CRT), liquid crystal display (LCD), plasma display, organic light-emitting diode (OLED) display, or another type of display device.

[0040] Although Figure 1 Not shown, but in some examples, the video encoder 200 and video decoder 300 may each integrate an audio encoder and / or audio decoder, and may include appropriate MUX-DEMUX units or other hardware and / or software to process multiplexed streams including both audio and video in a common data stream. Where applicable, the MUX-DEMUX unit may conform to any of the various multiplexer protocols.

[0041] Video encoder 200 and video decoder 300 each can be implemented as any of a variety of suitable encoder and / or decoder circuitry, such as one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), discrete logic, software, hardware, firmware or any combinations thereof. When the techniques are implemented partially in software, a device can store instructions for the software in a suitable, non- transitory computer-readable medium and execute the instructions in hardware using one or more processors to perform the techniques of this disclosure. Each of video encoder 200 and video decoder 300 can be included in one or more encoders or decoders, either of which can be integrated as part of a combined encoder / decoder (CODEC) in a respective device. A device including video encoder 200 and / or video decoder 300 can comprise an integrated circuit, a microprocessor, and / or a wireless communication device, such as a cellular telephone.

[0042] One example of a video coding standard is ITU-T H.265 (also known as the High Efficiency Video Coding (HEVC) standard) or extensions thereof, such as the multi-view or scalable video coding extensions. Video encoder 200 and video decoder 300 can operate according to other proprietary or industry standards, such as the ITU-T H.266 standard, also referred to as Versatile Video Coding (VVC). A recent draft of the VVC standard being developed is described in Bross, et al., “Versatile Video Coding (Draft 7),” JVET-P2001-vl4 (also sometimes referred to as JVET-P2001-vE), which was presented by the Joint Video Expert Team (JVET) of ITU-T SG 16 WP 3 and ISO / IEC JTC 1 / SC 29 at its 16th Meeting, held in Geneva, Switzerland, 1-11 October 2019 (hereinafter “VVC Draft 7”). A more recent draft of the VVC standard being developed is described in Bross, et al., “Versatile Video Coding Editorial Refinements on Draft 10,” JVET-T2001-vl l, which was presented by the Joint Video Expert Team (JVET) of ITU-T SG 16 WP 3 and ISO / IEC JTC 1 / SC 29 at its 20th Meeting, held by teleconference, 7-16 October 2020 (hereinafter “VVC Draft 10”). The techniques of this disclosure, however, are not limited to any particular coding standard.

[0043] In general, video encoder 200 and video decoder 300 can perform block-based coding of pictures. The term “block” generally refers to a structure including data to be processed (e.g., encoded, decoded, or otherwise used in the encoding and / or decoding process). For example, a block can include a two-dimensional matrix of samples of luma and / or chroma data, also referred to as luma components and chroma components. However, luma and chroma data is not required in all examples. For example, in monochrome formats, there can only be luma data (e.g., luma components) and no chroma data (e.g., no chroma components).

[0044] In general, video encoder 200 and video decoder 300 can code video data in YUV (e.g., Y, Cb, Cr) format or video data in Y only format for monochrome. That is, rather than coding red, green, and blue (RGB) data for samples of a picture, video encoder 200 and video decoder 300 can code luma and chroma components, where the chroma components can include both red hue and blue hue chroma components. In some examples, video encoder 200 converts received RGB formatted data to YUV representation before encoding, and video decoder 300 converts YUV representation to RGB format. Alternatively, pre- and post-processing units (not shown) can perform these conversions.

[0045] This disclosure can generally relate to coding (e.g., encoding and decoding) of pictures to include processes that encode or decode data of pictures. Similarly, this disclosure can relate to coding of blocks of pictures to include processes that encode or decode data for blocks (e.g., prediction and / or residual coding). An encoded video bitstream generally includes a series of values for syntax elements that represent coding decisions (e.g., coding modes) and partitioning of pictures into blocks. Accordingly, references to coding of pictures or blocks should generally be understood to code values of syntax elements that form the pictures or blocks.

[0046] HEVC defines various blocks, including coding units (CUs), prediction units (PUs), and transform units (TUs). According to HEVC, a video coder (such as video encoder 200) partitions a coding tree unit (CTU) into CUs according to a quad tree structure. That is, the video coder partitions a CTU and CUs into four equal, non overlapping squares, and each node of the quad tree has either zero or four child nodes. Nodes with zero child nodes can be referred to as“leaf nodes,” and CUs of such leaf nodes can include one or more PUs and / or one or more TUs. The video coder can further partition PUs and TUs. For example, in HEVC, a residual quad tree (RQT) represents partitioning of TUs. In HEVC, PUs represent inter-predicted data, while TUs represent residual data. CUs that are intra-predicted include intra-prediction information, such as an intra-mode indication.

[0047] As another example, video encoder 200 and video decoder 300 can be configured to operate according to VVC. According to VVC, a video coder (such as video encoder 200) partitions a picture into coding tree units (CTUs). Video encoder 200 can partition CTUs according to a tree structure, such as a quad-tree 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 in HEVC. The QTBT structure includes two levels: a first level partitioned according to quad tree partitioning, and a second level partitioned according to binary tree partitioning. The root node of the QTBT structure corresponds to a CTU. Leaf nodes of the binary trees correspond to coding units (CUs).

[0048] In the MTT partitioning structure, blocks can be partitioned using quad tree (QT) partitioning, binary tree (BT) partitioning, and one or more types of ternary tree (TT) partitioning (also referred to as triple tree (TT)). A ternary tree or triple tree partition is a partition in which a block is split into three sub-blocks. In some examples, a ternary tree or triple tree partition splits a block into three sub-blocks without splitting the original block through the center. The partition types (e.g., QT, BT, and TT) in the MTT can be symmetric or asymmetric.

[0049] In some examples, video encoder 200 and video decoder 300 can use a single QTBT or MTT structure to represent each of luma and chroma components, while in other examples, video encoder 200 and video decoder 300 can use two or more QTBT or MTT structures, such as one QTBT / MTT structure for luma components and another QTBT / MTT structure for two chroma components (or two QTBT / MTT structures for respective chroma components). That is, in examples where video encoder 200 and video decoder 300 utilize a single QTBT or MTT structure, video encoder 200 and video decoder 300 can be considered to utilize single tree partitioning. In examples where video encoder 200 and video decoder 300 utilize two or more QTBT or MTT structures, video encoder 200 and video decoder 300 can be considered to utilize dual tree partitioning. Accordingly, video encoder 200 and video decoder 300 can be configured to determine whether a current block is encoded with single tree partitioning or dual tree partitioning between single tree partitioning or dual tree partitioning.

[0050] Video encoder 200 and video decoder 300 can be configured to use quad tree partitioning, QTBT partitioning, MTT partitioning, or other partitioning structures per HEVC. For purposes of explanation, the description of the techniques of this disclosure is given with respect to QTBT partitioning. However, it should be understood that the techniques of this disclosure can also apply to video coders configured to use quad tree partitioning or also use other types of partitioning.

[0051] Blocks (e.g., CTUs or CUs) in an image can be grouped in various ways. As one example, a tile can refer to a rectangular region of CTU rows within a particular tile in an image. A tile can refer to a rectangular region of CTUs within a particular tile column and a particular tile row in an image. A tile column refers to a rectangular region of CTUs having a height equal to a height of an image and a width specified by a syntax element (e.g., such as in a picture parameter set). A tile row refers to a rectangular region of CTUs having a width specified by a syntax element (e.g., such as in a picture parameter set) and a height equal to a width of an image.

[0052] In some examples, a tile can be partitioned into multiple bricks, each of which can include one or more CTU rows within the tile. A tile that is not partitioned into multiple bricks can also be referred to as a brick. However, a brick that is a true subset of a tile can not be referred to as a tile.

[0053] The tiles in the image can also be arranged in slices. A slice can be an integer number of tiles of the image that can be uniquely contained in a single network abstraction layer (NAL) unit. In some examples, a slice includes a number of complete tiles or only a contiguous series of complete tiles of a single tile.

[0054] The disclosure can use“NxN” and“N by N” interchangeably to refer to the sample dimensions of a block (such as a CU or other video block) in the vertical and horizontal dimensions, e.g., 16x16 samples or 16 by 16 samples. In general, a 16x16 CU will have 16 samples in the vertical direction (y = 16) and 16 samples in the horizontal direction (x = 16). Likewise, an NxN CU generally has N samples in the vertical direction and N samples in the horizontal direction, where N represents a non negative integer value. The samples in a CU can be arranged in rows and columns. Moreover, a CU need not have the same number of samples in the horizontal direction as in the vertical direction. For example, a CU can comprise NxM samples, where M need not equal N.

[0055] Video encoder 200 encodes video data representing prediction and / or residual information for a CU, among other information. Prediction information indicates how to predict the CU in order to form a prediction block for the CU. Residual information generally represents a sample-by-sample difference between the CU prior to encoding and the prediction block.

[0056] To predict a CU, video encoder 200 can generally form a prediction block for the CU through inter-prediction or intra-prediction. Inter-prediction generally refers to predicting the CU from data of a previously coded picture, whereas intra-prediction generally refers to predicting the CU from previously coded data of the same picture. To perform inter-prediction, video encoder 200 can use one or more motion vectors to generate the prediction block. Video encoder 200 can generally perform a motion search to identify a reference block that closely matches the CU, e.g., according to a difference between the CU and the reference block. Video encoder 200 can calculate a difference metric using sum of absolute error (SAD), sum of squared error (SSD), mean absolute difference (MAD), mean squared difference (MSD), or other such difference calculations to determine whether a reference block closely matches a current CU. In some examples, video encoder 200 can use uni-prediction or bi-prediction to predict a current CU.

[0057] In some examples, VVC provides an affine motion compensation mode that can be considered a mode of inter-prediction. Under the affine motion compensation mode, video encoder 200 can determine two or more motion vectors that represent non-translational motion, such as scaling or zooming, rotation, perspective motion, or other irregular types of motion.

[0058] To perform intra prediction, video encoder 200 can select an intra prediction mode to generate the prediction block. In some examples, VVC provides sixty-seven intra prediction modes, including various directional modes, as well as a planar mode and a DC mode. Generally, video encoder 200 selects an intra prediction mode that describes samples neighboring the current block (e.g., a block of a CU) from which to predict the current block according to. Assuming that video encoder 200 is coding CTUs and CUs in a raster scan order (left-to-right, top-to-bottom), such samples can generally be above, above-and-left, or left of the current block in the same image as the current block.

[0059] Video encoder 200 encodes data representing the prediction mode used for the current block. For example, for inter prediction modes, video encoder 200 can encode data representing which of various available inter prediction modes to use, as well as motion information for the corresponding mode. For single or bi-directional inter prediction, for example, video encoder 200 can encode motion vectors using advanced motion vector prediction (AMVP) or merge mode. Video encoder 200 can use similar modes to encode motion vectors for affine motion compensation modes.

[0060] After prediction, such as intra or inter prediction of a block, video encoder 200 can calculate residual data for the block. Residual data, such as a residual block, represents sample-by-sample differences between the block and a prediction block formed using the corresponding prediction mode. Video encoder 200 can apply one or more transforms to the residual block to produce transformed data in a transform domain rather than in the sample domain. For example, video encoder 200 can apply a discrete cosine transform (DCT), an integer transform, a wavelet transform, or a conceptually similar transform. Additionally, video encoder 200 can apply a secondary transform, such as a mode-dependent non-separable secondary transform (MDNSST), a signal-dependent transform, a Karhunen-Loeve transform (KLT), or the like, following the first transform. Video encoder 200 produces transform coefficients following application of the transform(s).

[0061] As noted above, following any transforms to produce transform coefficients, video encoder 200 can perform quantization on 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 200 can reduce the bit depth of some or all of the transform coefficients. For example, video encoder 200 can 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 200 can perform a bitwise right-shift of the value to be quantized.

[0062] After quantization, video encoder 200 can scan the transform coefficients, producing a one-dimensional vector from the two-dimensional matrix including the quantized transform coefficients. The scan can be designed to place higher energy (and hence lower frequency) transform coefficients at the front of the vector, and lower energy (and hence higher frequency) transform coefficients at the back of the vector. In some examples, video encoder 200 can utilize a pre-defined 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 200 can perform an adaptive scan. After scanning the quantized transform coefficients to form a one-dimensional vector, video encoder 200 can entropy encode the one-dimensional vector, e.g., according to context adaptive binary arithmetic coding (CABAC). Video encoder 200 can also entropy encode values for syntax elements describing metadata associated with the encoded video data for use by video decoder 300 when decoding the video data.

[0063] To perform CABAC, video encoder 200 can assign a context within a context model to a symbol to be transmitted. The context can relate to, for example, whether neighboring values of the symbol are zero-valued or not. The probability determination can be based on the context assigned to the symbol.

[0064] Video encoder 200 can also generate syntax data, such as block-based syntax data, picture-based syntax data, and sequence-based syntax data, or other syntax data, such as a sequence parameter set (SPS), a picture parameter set (PPS), or a video parameter set (VPS), for video decoder 300, e.g., in a picture header, a block header, a slice header. Video decoder 300 can likewise decode such syntax data to determine how to decode corresponding video data.

[0065] In this way, video encoder 200 can generate a bitstream including encoded video data, e.g., syntax elements describing partitioning of a picture into blocks (e.g., CUs) and prediction and / or residual information for the blocks. Ultimately, video decoder 300 can receive the bitstream and decode the encoded video data.

[0066] In general, video decoder 300 performs a reciprocal process to that performed by video encoder 200 to decode the encoded video data of the bitstream. For example, video decoder 300 can decode values for syntax elements of the bitstream using CABAC in substantially a reciprocal manner to, but in reverse of, the CABAC encoding process of video encoder 200. The syntax elements can define partitioning information for partitioning a picture into CTUs, and partitioning each CTU according to a corresponding partition structure, such as a QTBT structure, to define CUs of the CTU. The syntax elements can further define prediction and residual information for blocks (e.g., CUs) of the video data.

[0067] The residual information can be represented by, for example, quantized transform coefficients. Video decoder 300 can inverse quantize and inverse transform the quantized transform coefficients of a block to reproduce a residual block for the block. Video decoder 300 forms a prediction block for the block using the signaled prediction mode (intra prediction or inter prediction) and related prediction information (e.g., motion information for inter prediction). Video decoder 300 can then combine the prediction block and the residual block (on a sample-by-sample basis) to reproduce the original block. Video decoder 300 can perform additional processing such as performing a deblocking process to reduce visual artifacts along boundaries of the blocks.

[0068] The above describes example techniques for video coding, such as with inter prediction and intra prediction. Another example video coding technique is palette mode coding. In applications such as remote desktop, collaborative work, and wireless display, computer-generated screen content (e.g., such as text or computer graphics) can be the dominant content to compress. This type of content tends to have discrete color tones and sharply defined lines and high-contrast object boundaries. The assumption of continuous tone and smoothness can no longer hold for screen content, and thus traditional video coding techniques can not be an efficient approach to compressing video data that includes screen content.

[0069] In general, palette coding is designed to handle the concentration of colors in screen content. Palette coding employs a palette of colors and an index map to represent an input image block. Video encoder 200 can quantize a sample to one of the colors in the palette of colors in the input block, and can generate an index map to indicate the corresponding color for each sample. Due to the sparse histogram of screen content, the coding cost is significantly reduced by the small number of colors in each block.

[0070] Video encoder 200 and video decoder 300 can code a table for a CU named "palette" (e.g., referred to as a palette mode table) to indicate the possible colors that can be present in the CU. The palette mode table can include color entries (e.g., sample values), each of which is represented by an index. The palette mode table can include color entries in any color format (e.g., RGB, YCbCr, or another color format). Video encoder 200 and video decoder 300 can use a prediction technique to code the palette to save bits. Thereafter, video encoder 200 and video decoder 300 can code samples (e.g., luma and chroma color components of pixels) in the current CU. Video encoder 200 can quantize the samples to one of the base colors in the palette. Video encoder 200 can then code an index corresponding to the base color. To more efficiently code the indices for all the samples, video encoder 200 can group the indices together as an index map and code the index map as a whole. Video encoder 200 and video decoder 300 can be configured to scan the samples in the index map horizontally or vertically in a rotated manner.

[0071] For monochrome formats, since there is no chroma component, the palette mode table can include sample values for luma component only. For other color formats that include chroma components, the palette mode table can include sample values for luma and chroma components. For example, video encoder 200 and video decoder 300 can determine a number of color components used for palette mode coding of a current block. The number of color components used for palette mode coding of a current block can refer to the number of color components included in the palette mode table. For monochrome, the number of color components used for palette mode coding can be one (e.g., luma only), and for other color formats that include luma and chroma components, the number of color components used for palette mode coding can be three (e.g., luma component and two chroma components).

[0072] Video encoder 200 can be configured to determine to apply an INDEX mode to signal an index for a particular sample. Video encoder 200 can also determine to use a COPY ABOVE mode. In the COPY ABOVE mode, the index for a sample is copied from the index of a neighboring sample above it. Video encoder 200 can signal a bit indicating which mode is used for a particular sample. To further reduce bits, several consecutive samples can share the same mode. Video encoder 200 can code a run length indicating how many consecutive samples share the same mode. If the current sample utilizes the INDEX mode, the number of consecutive samples indicated by the run length will share the same index as the current sample. If the current sample utilizes the COPY ABOVE mode, the number of consecutive samples indicated by the run length will share the COPY ABOVE mode, i.e., video decoder 300 will copy the index from the neighboring sample above it for these samples. Additionally, a sample can also be coded directly in ESCAPE mode (i.e., video encoder 200 can directly encode the sample value) to handle exceptional cases (e.g., the sample value is not in the palette mode table).

[0073] According to the techniques of this disclosure, palette mode can be enabled for monochrome content and / or when separate color plane coding is used. For example, video encoder 200 and video decoder 300 can determine that one or more blocks are for monochrome content (e.g., have a monochrome color format or are coded as monochrome content) and / or determine that one or more blocks are for separate color plane coding (e.g., there are multiple color planes, and one or more blocks are for at least one of the color planes). Video encoder 200 or video decoder 300 can utilize palette mode to code (e.g., encode for video encoder 200 or decode for video decoder 300) the one or more blocks.

[0074] For example, as described above, in one or more examples, the color format and the partition tree type can be factors in determining a number of color components for palette mode coding. According to one or more examples, a video coder (e.g., video encoder 200 or video decoder 300) can determine that a current block of video data is coded in a palette mode, and determine, between a single tree partition or a dual tree partition, that the current block is coded with the single tree partition enabled. In such an example, the video coder can determine that the current block is coded in a monochrome format. When the current block is coded with the single tree partition enabled and when the current block is coded in the monochrome format, the video coder can determine that the number of color components for palette mode coding of the current block is equal to one. The video coder can palette mode code (e.g., encode or decode) the current block based on the determined number of color components for palette mode coding of the current block being equal to one.

[0075] As one example, to palette mode code the current block, the video coder can palette mode code the current block based on a palette mode table for only the luma component. For example, video decoder 300 can receive an index for a palette mode table for a sample in the current block, and assign a luma value to the sample in the current block based on the index for the palette mode table. Video encoder 200 can determine a luma value for a sample in the current block, determine an index for a palette mode table based on the determined luma value for the sample, and signal information indicating the index for the palette mode table for the sample in the current block.

[0076] The present disclosure can generally relate to “signaling” certain information, such as syntax elements. The term “signaling” can generally refer to the communication of values for syntax elements and / or other data used to decode encoded video data. That is, video encoder 200 can signal values for syntax elements in a bitstream. Generally, signaling refers to generating values in a bitstream. As noted above, source device 102 can transmit the bitstream to destination device 116 in substantially real time or not in real time, such as can occur when syntax elements are stored to storage device 112 to be retrieved by destination device 116 at a later time.

[0077] Figure 2A and Figure 2Bis a conceptual diagram illustrating an example quadtree-binary tree (QTBT) structure 130 and a corresponding coding tree unit (CTU) 132. The solid lines indicate quadtree splits, and the dashed lines indicate binary tree splits. In each split (i.e., non-leaf) node of the binary tree, a flag is signaled to indicate which split type (i.e., horizontal or vertical) is used, where 0 indicates a horizontal split and 1 indicates a vertical split in this example. For quadtree splits, the split type does not need to be indicated because quadtree nodes split a block horizontally and vertically into 4 equal-sized sub-blocks. Accordingly, video encoder 200 can encode, and video decoder 300 can decode, syntax elements (such as split information) for the region tree level (i.e., the solid lines) of the QTBT structure 130, as well as syntax elements (such as split information) for the prediction tree level (i.e., the dashed lines) of the QTBT structure 130. Video encoder 200 can encode, and video decoder 300 can decode, video data (such as prediction and transform data) for CUs represented by terminal leaf nodes of the QTBT structure 130.

[0078] In general, Figure 2B The CTU 132 can be associated with parameters defining sizes of blocks corresponding to nodes at the first and second levels of the QTBT structure 130. These parameters can include a CTU size (representing the size of the CTU 132 in units of samples), a minimum quadtree size (MinQTSize, representing the minimum allowed quadtree leaf node size), a maximum binary tree size (MaxBTSize, representing the maximum allowed binary tree root node size), a maximum binary tree depth (MaxBTDepth, representing the maximum allowed binary tree depth), and a minimum binary tree size (MinBTSize, representing the minimum allowed binary tree leaf node size).

[0079] A root node of the QTBT structure corresponding to a CTU can have four child nodes at a first level of the QTBT structure, each of which can be partitioned according to quadtree partitioning. That is, a node at the first level is either a leaf node (having no child nodes) or has four child nodes. The example of QTBT structure 130 represents such nodes as including parent and child nodes with solid lines for branches. If a node at the first level is not larger than a maximum allowed binary tree root node size (MaxBTSize), the node can be further partitioned by a corresponding binary tree. Binary tree splitting for a node can be iterated until nodes resulting from the splitting reach a minimum allowed binary tree leaf node size (MinBTSize) or a maximum allowed binary tree depth (MaxBTDepth). The example of QTBT structure 130 represents such nodes as having dashed lines for branches. Binary tree leaf nodes are referred to as coding units (CUs), which are used for prediction (e.g., intra-picture or inter-picture prediction) and transform without any further partitioning. As discussed above, a CU can also be referred to as a “video block” or “block.”

[0080] In one example of a QTBT partitioning structure, the CTU size is set to 128x128 (luma samples and two corresponding 64x64 chroma samples), MinQTSize is set to 16x16, MaxBTSize is set to 64x64, MinBTSize (for both width and height) is set to 4, and MaxBTDepth is set to 4. Quadtree partitioning is first applied to the CTU to generate quadtree leaf nodes. The quadtree leaf nodes can have sizes from 16x16 (i.e., MinQTSize) to 128x128 (i.e., the CTU size). If a leaf quadtree node is 128x128, the leaf quadtree node will not be further split by binary trees because the size exceeds MaxBTSize (i.e., 64x64 in this example). Otherwise, the leaf quadtree node will be further partitioned by binary trees. Thus, a quadtree leaf node is also a root node for binary trees, and has a binary tree depth of 0. When the binary tree depth reaches MaxBTDepth (4 in this example), no further splitting is allowed. When a binary tree node has a width equal to MinBTSize (4 in this example), this means that no further horizontal splitting is allowed. Similarly, a binary tree node with a height equal to MinBTSize means that no further vertical splitting is allowed for that binary tree node. As noted above, leaf nodes of binary trees are referred to as CUs, and are further processed according to prediction and transform without further partitioning.

[0081] VVC Draft 7 describes palette mode applied to 4:4:4 content (e.g., luma component and chroma components have the same size). VVC Draft 7 already supports luma-only mode when dual tree partitioning is enabled. For example, in the case of dual tree partitioning enabled, luma component and chroma components can be partitioned in different ways. Accordingly, in some examples, palette mode can be applied together with dual tree partitioning such that palette mode coding is applied separately to each of luma component and chroma components because the partitioning of luma component and chroma components is different.

[0082] As described above, dual tree partitioning can be the case that luma component and chroma components are partitioned in different ways. In single tree partitioning, luma component and chroma components are partitioned in the same way. However, VVC Draft 7 can not support palette mode, and palette mode is not applied for monochrome content and when separate color plane coding is used. Monochrome content is also referred to as 4:0:0 chroma format or chroma sampling type.

[0083] In some examples, palette mode, dual tree partitioning and separate color plane coding control flag are signaled in SPS (Sequence Parameter Set). The following is an example of signaling.

[0084]

[0085]

[0086] sps_palette_enabled_flag equal to 1 specifies that pred_mode_plt_flag can be present in the coding unit syntax. sps_palette_enabled_flag equal to 0 specifies that pred_mode_plt_flag is not present in the coding unit syntax. When sps_palette_enabled_flag is not present, it is inferred to be equal to 0.

[0087] qtbtt_dual_tree_intra_flag equal to 1 specifies that for I slices, each CTU is split using implicit quadtree splitting into coding units with 64x64 luma samples, and these coding units are roots of two separate coding tree syntax structures for luma and chroma. qtbtt_dual_tree_intra_flag equal to 0 specifies that separate coding tree syntax structures are not used for I slices. When qtbtt_dual_tree_intra_flag is not present, it is inferred to be equal to 0.

[0088] separate_colour_plane_flag equal to 1 specifies that the three colour components of the 4:4:4 chroma format are coded separately. separate_colour_plane_flag equal to 0 specifies that the colour components are not coded separately. When separate_colour_plane_flag is not present, it is inferred to be equal to 0. When separate_colour_plane_flag is equal to 1, the coded picture includes three separate components, each of which includes coded samples of one colour plane (Y, Cb or Cr) and uses monochrome coding syntax. In this case, each colour plane is associated with a particular colour_plane_id value.

[0089] In some examples, there is no dependency between colour planes having different colour_plane_id values in the decoding process. For example, the decoding process for a monochrome picture having one value of colour_plane_id does not use any data from a monochrome picture having a different colour_plane_id value for inter prediction.

[0090] Depending on the value of separate_colour_plane_flag, the value of the variable ChromaArrayType is assigned as follows:

[0091] - If separate_colour_plane_flag is equal to 0, ChromaArrayType is set equal to chroma_format_idc.

[0092] - Otherwise (separate_colour_plane_flag is equal to 1), ChromaArrayType is set equal to 0.

[0093] When separate_colour_plane_flag is set to 1, the three colour planes are handled separately as monochrome sampled pictures.

[0094] There can be issues in VVC Draft 7 in terms of palette mode coding. Palette mode is not applied to monochrome content and separate color plane coding. Since palette mode for luma-only mode when dual tree partitioning is enabled is already supported in VVC Draft 7, it can be possible to enable palette mode for monochrome content and when separate color plane coding is used. For example, palette mode can not be applicable to monochrome content and separate color plane coding. There can be no drawback in enabling palette mode for monochrome content and using separate color plane since palette mode in separate luma-only mode is already supported when dual tree is enabled.

[0095] According to examples described in the present disclosure, palette mode is enabled for monochrome content and for separate color plane coding, where each plane can be treated as a monochrome signal. In some examples, the present disclosure describes examples of reusing the existing luma-only palette mode (which is used for dual tree partitioning) where the luma component and the chroma component can be coded separately in I slices. In one or more examples, when monochrome content is the input, the luma-only operational mode for palette mode is extended for single tree coding (in VVC, dual tree is disabled for monochrome and separate color plane coding).

[0096] Video encoder 200 and video decoder 300 can identify monochrome content by assigning (e.g., by video encoder 200) or checking (e.g., by video decoder 300) a chroma format idc value (chroma format idc = 0 indicates monochrome) or by assigning or checking a separate color plane flag (separate colour plane flag = 1 indicates that each color plane is coded as monochrome content).

[0097] To enable luma-only palette mode for monochrome content and separate color plane coding, in one example, video encoder 200 and video decoder 300 can define (e.g., determine) the number of color components involved in palette mode based on tree type and chroma format idc condition check. For example, if it is single tree (separate tree or dual tree disabled) type coding and chroma format idc is equal to 0, the number of color components in palette is set to 1; otherwise it is set to 3.

[0098] In other words, when the current block is coded with single tree partition enabled and when the current block is coded in monochrome format, video encoder 200 and video decoder 300 can determine that the number of color components used for palette mode coding of the current block is equal to one. When the current block is coded with single tree partition enabled and when the current block is not coded in monochrome format, video encoder 200 and video decoder 300 can determine that the number of color components used for palette mode coding of the current block is equal to three.

[0099] In VVC Draft 7, in one example, palette mode can be implemented as follows, where the addition is shown as text between <add>With< / add>

[0100] numComps = (treeType == SINGLE_TREE)? ( <add>ChromaArrayType == 0? 1< / add> : 3) : (treeType == DUAL_TREE_CHROMA)? 2 : 1

[0101] (treeType == DUAL_TREE_CHROMA)? 2 : 1

[0102] In the above example, the derived number of color components can be used in palette mode syntax signaling.

[0103] For example, in the following operation: numComps = (treeType == SINGLE_TREE)? (ChromaArrayType == 0? 1 : 3) : (treeType == DUAL_TREE_CHROMA)? 2 : 1, numComps is equal to the number of color components used for palette mode coding (e.g., the number of color components involved in palette mode). The number of color components used for palette mode coding can refer to the number of color components included in a palette mode table.

[0104] In the above operation for determining numComps, the value of numComps is based on the partition tree type (e.g., whether it is single tree partition) and whether the block is in monochrome format (e.g., whether ChromaArrayType is 0). For example, the above operation for numComps can be parsed as follows. If the partition tree type is single tree partition (e.g., treeType == SINGLE_TREE), a determination is made as to whether the block is coded in monochrome format (e.g., ChromaArrayType == 0). When the partition tree type is single tree partition and when the block is coded in monochrome format, then the number of color components used for palette mode coding of the current block is equal to one.

[0105] ​For example, video encoder 200 and video decoder 300 can determine that a current block of video data is coded in palette mode, and can determine that the current block is coded with single tree partitioning enabled (e.g., treeType == SINGLE_TREE) between single tree partitioning or dual tree partitioning. Video encoder 200 and video decoder 300 can determine that the current block is coded in monochrome format. As one example, in response to determining that the current block is coded with single tree partitioning enabled, video encoder 200 and video decoder 300 can determine that the current block is coded in monochrome format (e.g., in response to treeType being equal to SINGLE_TREE, video encoder 200 and video decoder 300 can determine that ChromaArrayType is equal to 0).

[0106] When the current block is coded with single tree partitioning enabled and when the current block is coded in monochrome format, video encoder 200 and video decoder 300 can determine that the number of color components for palette mode coding of the current block is equal to one. For example, in response to determining that the current block is coded with single tree partitioning enabled and in response to determining that the current block is coded in monochrome format (e.g., in response to treeType being equal to SINGLE_TREE and ChromaArrayType being equal to 0), video encoder 200 and video decoder 300 can determine that the current block is coded in monochrome format, determine that the number of color components for palette mode coding is equal to one (e.g., numComps is equal to 1).

[0107] In another example, for the number of color components equal to 3 or assumed to be equal to 3, the number of color components involved in palette mode processing can be modified for video encoder 200 or video decoder 300. In such an example, chroma format idc is further checked and if it is equal to 0 (i.e., monochrome content), the number of color components in palette mode is set to 1.

[0108] In one example, the above techniques can be implemented as follows, with changes to VVC Draft 7 shown with additional language in <add>And< / add>

[0109] Depending on the value of treeType, the variables startComp and numComps are derived as follows:

[0110] - If treeType is equal to SINGLE_TREE:

[0111] startComp = 0 (444) ​

[0112] numComps = <add>ChromaArrayType == 0? 1< / add> :3(445)

[0113] In this example, the derived number of color components can be used during the decoding process in palette mode. These two examples of deriving the number of color components in palette mode can be used together.

[0114] In some examples, these two modifications can be implemented for the palette mode in VVC Draft 7 to support monochrome and separate color plane decoding. The changes to VVC Draft 7 are described below using... <add>And< / add> The additional languages ​​shown within.

[0115] 7.3.9.6. Palette Decoding Syntax

[0116]

[0117] 8.4.5.3 Decoding process for palette mode

[0118] The input to this process is:

[0119] – Position(xCbComp, yCbComp), which specifies the top-left sample of the current decoded block relative to the top-left sample of the current image.

[0120] The variable `treeType` specifies whether a single-tree or dual-tree system is used. If a dual-tree system is used, it specifies whether the current tree corresponds to the luminance or chrominance components.

[0121] – The variable cIdx specifies the color component of the current block.

[0122] – Two variables, nCbW and nCbH, specify the width and height of the current decoded block, respectively.

[0123] The output of this process is an array recSamples[x][y] (where x = 0..nCbW-1, y = 0..nCbH-1), which specifies the reconstructed sample values ​​used for the block.

[0124] Depending on the value of treeType, the variables startComp and numComps are derived as follows:

[0125] –If treeType equals SINGLE_TREE:

[0126] Then startComp = 0 (444)

[0127] numComps = <add>ChromaArrayType == 0? 1< / add> 3 (445)

[0128] - Otherwise, treeType is equal to DUAL_TREE_LUMA:

[0129] startComp = 0 (446)

[0130] numComps = 1 (447)

[0131] - Otherwise, treeType is equal to DUAL_TREE_CHROMA:

[0132] startComp = 1 (448)

[0133] numComps = 2 (449)

[0134] As seen above, numComps = (treeType == SINGLE_TREE)? (ChromaArrayType == 0? 1 : 3) : (treeType == DUAL_TREE_CHROMA)? 2 : 1 is part of the palette mode coding syntax structure (e.g., 7.3.9.6. Palette coding syntax referenced above). Accordingly, in one or more examples, video decoder 300 can be configured to perform operations defined in the palette mode coding syntax structure (e.g., operations of 7.3.9.6 Palette coding syntax, as one non-limiting example). In such examples, when a current block is coded with single tree partitioning enabled and when the current block is coded in a single color, video encoder 200 and video decoder 300 can determine a number of color components (e.g., numComps) used for palette mode coding of the current block to be equal to one as part of performing operations defined in the palette mode coding syntax structure. For example, video encoder 200 and video decoder 300 can determine a value of numComps to be equal to one based on determining numComps = (treeType == SINGLE_TREE)? (ChromaArrayType == 0? 1 : 3) : (treeType == DUAL_TREE_CHROMA)? 2 : 1 as part of performing operations defined in the palette mode coding syntax structure.

[0135] In the example described above, the current block can be considered a first block. For a second block, video encoder 200 and video decoder 300 can determine that the second block is coded in palette mode and determine between single tree partitioning or dual tree partitioning that the second block is coded with single tree partitioning enabled.

[0136] However, in this example, video encoder 200 and video decoder 300 can determine that the second block is not coded in monochrome format (e.g., ChromaArrayType is not equal to 0). In this example, when the second block is coded with single tree partitioning enabled and when the second block is not coded in monochrome format, video encoder 200 and video decoder 300 can determine that the number of color components used for palette mode coding of the second block (e.g., numComps for the second block) is equal to three. That is, numComps is equal to 3 because treeType is SINGLE_TREE and ChromaArrayType is not 0.

[0137] Figure 3 FIG. 1 is a block diagram illustrating an example video encoder 200 that can perform the techniques of this disclosure. Figure 3 FIG. 1 is a block diagram illustrating an example video encoder 200 that can perform the techniques of this disclosure.

[0138] In Figure 3 In the example of FIG. 1, video encoder 200 includes video data memory 230, mode select unit 202, residual generation unit 204, transform processing unit 206, quantization unit 208, inverse quantization unit 210, inverse transform processing unit 212, reconstruction unit 214, filter unit 216, decoded picture buffer (DPB) 218, and entropy encoding unit 220. Any or all of video data memory 230, mode select unit 202, residual generation unit 204, transform processing unit 206, quantization unit 208, inverse quantization unit 210, inverse transform processing unit 212, reconstruction unit 214, filter unit 216, DPB 218, and entropy encoding unit 220 can be implemented in one or more processors or in processing circuitry. For instance, the units of video encoder 200 can be implemented as one or more circuits or logic elements as part of hardware circuitry, or as part of a processor, ASIC, or FPGA. Also, video encoder 200 can include additional or alternative processors or processing circuitry to perform these and other functions.

[0139] Video data memory 230 can store video data to be encoded by the components of video encoder 200. Video encoder 200 can receive the video data from, for example, video source 104 Figure 1The video data is stored in the video data memory 230. The DPB 218 can act as a reference image memory, storing reference video data for use when the video encoder 200 predicts subsequent video data. The video data memory 230 and DPB 218 can consist of any of a variety of memory devices, such as dynamic random access memory (DRAM) (including synchronous DRAM (SDRAM)), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. The video data memory 230 and DPB 218 can be provided by the same memory device or separate memory devices. In various examples, the video data memory 230 can be on-chip (as shown) along with other components of the video encoder 200, or off-chip relative to those components.

[0140] In this disclosure, references to video data memory 230 should not be construed as limited to memory internal to video encoder 200 (unless explicitly stated otherwise) or memory external to video encoder 200 (unless explicitly stated otherwise). More precisely, references to video data memory 230 should be understood as reference memory storing video data received by video encoder 200 for encoding (e.g., video data for the current block to be encoded). Figure 1 The memory 106 can also provide temporary storage for the outputs from various units of the video encoder 200.

[0141] Show Figure 3 Various units are provided to aid in understanding the operations performed by the video encoder 200. These units can be implemented as fixed-function circuits, programmable circuits, or a combination thereof. Fixed-function circuits are circuits that provide specific functions and are pre-configured according to the operations that can be performed. Programmable circuits are circuits that can be programmed to perform various tasks and provide flexible functionality in terms of the operations that can be performed. For example, a programmable circuit can execute software or firmware that causes the programmable circuit to operate in a manner defined by instructions in the software or firmware. Fixed-function circuits can execute software instructions (e.g., to receive or output parameters), but the type of operation performed by a fixed-function circuit is typically immutable. In some examples, one or more units in the unit may be different circuit blocks (fixed-function or programmable), and in some examples, one or more units in the unit may be integrated circuits.

[0142] Video encoder 200 can include arithmetic logic units (ALUs), elementary function units (EFUs), digital circuits, analog circuits, and / or programmable cores, composed of programmable circuitry. In examples where operations of video encoder 200 are performed using software executed by the programmable circuitry, memory 106 Figure 1 ) can store instructions (e.g., object code) for the software that video encoder 200 receives and executes, or another memory within video encoder 200 (not shown) can store such instructions.

[0143] Video data memory 230 is configured to store received video data. Video encoder 200 can retrieve a picture of video data from video data memory 230 and provide the video data to residual generation unit 204 and mode selection unit 202. Video data in video data memory 230 can be raw video data that is to be encoded.

[0144] Mode selection unit 202 includes motion estimation unit 222, motion compensation unit 224, and intra-prediction unit 226. Mode selection unit 202 can include additional functional units to perform video prediction according to other prediction modes. As examples, mode selection unit 202 can include a palette unit, an intra-block copy unit (which can be part of motion estimation unit 222 and / or motion compensation unit 224), an affine unit, a linear model (LM) unit, etc.

[0145] Mode selection unit 202 generally coordinates multiple coding passes to test combinations of coding parameters and rate-distortion values resulting for such combinations. Coding parameters can include partitioning of CTUs into CUs, prediction modes for CUs, transform types for residual data of CUs, quantization parameters for residual data of CUs, etc. Mode selection unit 202 can ultimately select the combination of coding parameters of a combination that has a better rate-distortion value than other tested combinations.

[0146] Video encoder 200 can partition a picture retrieved from video data memory 230 into a series of CTUs, and encapsulate one or more CTUs within a slice. Mode selection unit 202 can partition CTUs of a picture according to a tree structure, such as the QTBT structure or quad-tree structure of HEVC described above. As described above, video encoder 200 can form one or more CUs from partitioning a CTU according to the tree structure. Such CUs can also be referred to generally as “video blocks” or “blocks.”

[0147] In general, mode selection unit 202 also controls its components (e.g., motion estimation unit 222, motion compensation unit 224, and intra-prediction unit 226) to generate a prediction block for a current block (e.g., a current CU, or in HEVC, an overlapping portion of a PU and a TU). To perform inter-prediction for the current block, motion estimation unit 222 can perform a motion search to identify one or more closely matching reference blocks in one or more reference images (e.g., one or more previously coded images that are stored in DPB 218). In particular, motion estimation unit 222 can compute values that represent how similar a potential reference block is to the current block, e.g., according to sum of absolute error (SAD), sum of squared error (SSD), mean absolute difference (MAD), mean squared difference (MSD), etc. Motion estimation unit 222 can generally perform these computations using sample-wise differences between the current block and a reference block under consideration. Motion estimation unit 222 can identify the reference block with the lowest value resulting from these computations, indicating the reference block that most closely matches the current block.

[0148] Motion estimation unit 222 can form one or more motion vectors (MVs) that define a position of a reference block in a reference image relative to a position of the current block in the current image. Motion estimation unit 222 can then provide the motion vector(s) to motion compensation unit 224. For example, for single-direction inter-prediction, motion estimation unit 222 can provide a single motion vector, while for bi-directional inter-prediction, motion estimation unit 222 can provide two motion vectors. Motion compensation unit 224 can then use the motion vector(s) to generate the prediction block. For example, motion compensation unit 224 can use the motion vector(s) to retrieve data for the reference block. As another example, if the motion vector has fractional sample precision, motion compensation unit 224 can interpolate values for the prediction block according to one or more interpolation filters. Moreover, for bi-directional inter-prediction, motion compensation unit 224 can retrieve data for two reference blocks identified by respective motion vectors, and combine the retrieved data, e.g., by sample-wise averaging or weighted averaging.

[0149] As another example, for intra-prediction or intra-prediction coding, intra-prediction unit 226 can generate the prediction block from samples neighboring the current block. For example, for directional modes, intra-prediction unit 226 can generally arithmetically combine values of the neighboring samples and fill these computed values in a defined direction across the current block to produce the prediction block. As another example, for a DC mode, intra-prediction unit 226 can compute an average of the samples neighboring the current block, and generate the prediction block to include this resulting average for each sample of the prediction block.

[0150] The mode selection unit 202 provides the prediction block to a residual generation unit 204. The residual generation unit 204 receives the original, uncoded version of the current block from the video data memory 230 and the prediction block from the mode selection unit 202. The residual generation unit 204 computes the sample-wise difference between the current block and the prediction block. The resulting sample-wise difference defines the residual block for the current block. In some examples, the residual generation unit 204 can also determine the difference between sample values in the residual block to generate the residual block using residual differential pulse code modulation (RDPCM). In some examples, the residual generation unit 204 can be formed using one or more subtractor circuits that perform binary subtraction.

[0151] In examples where the mode selection unit 202 partitions the CU into PUs, each PU can be associated with a luma prediction unit and corresponding chroma prediction units. Video encoder 200 and video decoder 300 can support PUs having various sizes. As indicated above, the size of a CU can refer to the size of the CU's luma coding block, and the size of a PU can refer to the size of the PU's luma prediction unit. Assuming that a particular CU has a size of 2Nx2N, video encoder 200 can support PU sizes of 2Nx2N or NxN for intra prediction, and 2Nx2N, 2NxN, Nx2N, NxN, or similar symmetric PU sizes for inter prediction. Video encoder 200 and video decoder 300 can also support asymmetric partitioning for PU sizes of 2NxnU, 2NxnD, nLx2N, and nRx2N for inter prediction.

[0152] In examples where the mode selection unit 202 does not further partition the CU into PUs, each CU can be associated with a luma coding block and corresponding chroma coding blocks. As above, the size of a CU can refer to the size of the CU's luma coding block. Video encoder 200 and video decoder 300 can support CU sizes of 2Nx2N, 2NxN, or Nx2N.

[0153] For other video coding techniques (such as intra block copy mode coding, affine mode coding, and linear model (LM) mode coding, to name a few), the mode selection unit 202 generates the prediction block for the current block being encoded via a respective unit associated with the coding technique. In some examples (such as palette mode coding), the mode selection unit 202 can not generate a prediction block, but instead generate syntax elements indicative of the way in which to reconstruct the block based on a selected palette. In such modes, the mode selection unit 202 can provide the syntax elements to the entropy encoding unit 220 for encoding.

[0154] As described above, the residual generation unit 204 receives video data for a current block and a corresponding prediction block. The residual generation unit 204 then generates a residual block for the current block. To generate the residual block, the residual generation unit 204 computes a sample-by-sample difference between the prediction block and the current block.

[0155] The transform processing unit 206 applies one or more transforms to the residual block to generate a block of transform coefficients (referred to herein as a "transform coefficient block"). The transform processing unit 206 can apply various transforms to the residual block to form a transform coefficient block. For example, the transform processing unit 206 can apply a discrete cosine transform (DCT), a directional transform, a Karhunen-Loeve transform (KLT), or a conceptually similar transform to the residual block. In some examples, the transform processing unit 206 can perform multiple transforms on the residual block, e.g., a primary transform and a secondary transform such as a rotation transform. In some examples, the transform processing unit 206 does not apply a transform to the residual block.

[0156] The quantization unit 208 can quantize the transform coefficients in the transform coefficient block to produce a quantized transform coefficient block. The quantization unit 208 can quantize transform coefficients of the transform coefficient block according to a quantization parameter (QP) value associated with the current block. The video encoder 200 (e.g., via the mode selection unit 202) can adjust the degree of quantization applied to the transform coefficient block associated with the current block by adjusting the QP value associated with the CU. Quantization can introduce loss of information, and thus, quantized transform coefficients can have lower precision than the original transform coefficients produced by the transform processing unit 206.

[0157] The inverse quantization unit 210 and inverse transform processing unit 212 can apply inverse quantization and inverse transforms, respectively, to a quantized transform coefficient block to reconstruct a residual block from the transform coefficient block. The reconstruction unit 214 can generate a reconstructed block corresponding to the current block (albeit potentially with some degree of distortion) based on the reconstructed residual block and the prediction block generated by the mode selection unit 202. For example, the reconstruction unit 214 can add samples of the reconstructed residual block to corresponding samples from the prediction block generated by the mode selection unit 202 to produce the reconstructed block.

[0158] The filter unit 216 can perform one or more filter operations on the reconstructed block. For example, the filter unit 216 can perform a deblocking operation to reduce blocking artifacts along the edges of the CU. In some examples, the operations of the filter unit 216 can be skipped.

[0159] Video encoder 200 stores the reconstructed blocks in DPB 218. For instance, in examples where the operations of filter unit 216 are not needed, reconstruction unit 214 can store the reconstructed blocks to DPB 218. In examples where the operations of filter unit 216 are needed, filter unit 216 can store the filtered reconstructed blocks to DPB 218. Motion estimation unit 222 and motion compensation unit 224 can retrieve reference pictures composed of reconstructed (and potentially filtered) blocks from DPB 218 to inter-predict blocks of subsequent encoded pictures. In addition, intra-prediction unit 226 can use reconstructed blocks of the current picture in DPB 218 to intra-predict other blocks in the current picture.

[0160] In general, entropy encoding unit 220 can entropy encode syntax elements received from other functional components of video encoder 200. For example, entropy encoding unit 220 can entropy encode quantized transform coefficient blocks from quantization unit 208. As another example, entropy encoding unit 220 can entropy encode prediction syntax elements (e.g., motion information for inter-prediction or intra-mode information for intra-prediction) from mode select unit 202. Entropy encoding unit 220 can perform one or more entropy encoding operations on the syntax elements, which are another example of video data, to generate entropy encoded data. For example, entropy encoding unit 220 can perform a context- adaptive variable length coding (CAVLC) operation, a CABAC operation, a variable to variable (V2V) length coding operation, a syntax-based context-adaptive binary arithmetic coding (SBAC) operation, a Probability Interval Partitioning Entropy (PIPE) coding operation, an Exponential-Golomb coding operation, or another type of entropy encoding operation on the data. In some examples, entropy encoding unit 220 can work in a bypass mode where the syntax elements are not entropy encoded.

[0161] Video encoder 200 can output a bitstream that includes the entropy encoded syntax elements needed to reconstruct blocks of a slice or picture. In particular, entropy encoding unit 220 can output the bitstream.

[0162] The operations described above are described with respect to blocks. Such description should be understood to be operations for luma coding blocks and / or chroma coding blocks. As described above, in some examples, the luma coding blocks and chroma coding blocks are luma components and chroma components of CUs. In some examples, the luma coding blocks and chroma coding blocks are luma components and chroma components of PUs.

[0163] In some examples, operations performed with respect to luma coding blocks need not be repeated for chroma coding blocks. As one example, operations to identify a motion vector (MV) and a reference picture for a luma coding block need not be repeated to identify an MV and a reference picture for a chroma block. Rather, the MV for the luma coding block can be scaled to determine the MV for the chroma block, and the reference picture can be the same. As another example, the intra prediction process for luma coding blocks and chroma coding blocks can be the same.

[0164] Video encoder 200 represents an example of a device configured to encode video data, the device comprising a memory configured to store video data and one or more processing units implemented in circuitry and configured to determine that one or more blocks are for (e.g., contain or include) monochrome content and encode the one or more blocks with a palette mode. In some examples, to determine that the one or more blocks are for monochrome content, the processing unit can be configured to determine (e.g., assign) a value for a chroma format (e.g., chroma format idc), where the value indicates that the one or more blocks are for monochrome content. In some examples, to determine that the one or more blocks are for monochrome content, the processing unit can determine (e.g., assign) a value for a separate color plane flag, where the value indicates that each color plane is coded as monochrome content, and where at least one color plane includes the one or more blocks. In some examples, the processing unit can be configured to determine that the one or more blocks are for separate color plane coding and encode the one or more blocks with the palette mode. In some examples, the processing unit can be configured to determine a number of color components for the palette mode based on at least one of a tree type or a chroma format.

[0165] For example, Figure 3 A palette mode unit 227 is shown, which can be configured in conjunction with other components, such as the mode selection unit 202, to perform example techniques described in this disclosure, such as the palette mode coding described above. As one example, the mode selection unit 202 can determine that a current block of video data is coded with a palette mode, and determine between a single tree partitioning or a dual tree partitioning that the current block is coded with the single tree partitioning enabled. For example, the mode selection unit 202 can test various coding passes, and determine that the palette mode with the single tree partitioning provides the best rate-distortion based on the coding passes.

[0166] In some examples, when the current block is coded with single tree partition enabled and when the current block is coded in monochrome format, the mode selection unit 202 can determine that the number of color components used for palette mode encoding of the current block is equal to one. The palette mode unit 227 can decode the current block in palette mode based on the determined number of color components used for palette mode decoding of the current block being equal to one.

[0167] Figure 4 FIG. 3 is a block diagram illustrating an example video decoder 300 that can perform the techniques of this disclosure. Figure 4 FIG. 3 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 300 according to the techniques of VVC (ITU-T H.266, in development) and HEVC (ITU-T H.265). However, the techniques of this disclosure can be performed by video coding devices configured to other video coding standards.

[0168] In Figure 4 In the example of FIG. 3, video decoder 300 includes coded picture buffer (CPB) memory 320, entropy decoding unit 302, prediction processing unit 304, inverse quantization unit 306, inverse transform processing unit 308, reconstruction unit 310, filter unit 312, and decoded picture buffer (DPB) 314. Any or all of CPB memory 320, entropy decoding unit 302, prediction processing unit 304, inverse quantization unit 306, inverse transform processing unit 308, reconstruction unit 310, filter unit 312, and DPB 314 can be implemented in one or more processors or in processing circuitry. For instance, the units of video decoder 300 can be implemented as one or more circuits or logic elements as part of hardware circuitry, or as part of a processor, ASIC, or FPGA. Also, video decoder 300 can include additional or alternative processors or processing circuitry to perform these and other functions.

[0169] Prediction processing unit 304 includes motion compensation unit 316 and intra-prediction unit 318. Prediction processing unit 304 can include additional units to perform prediction from other prediction modes. As examples, prediction processing unit 304 can include a palette unit, an intra-block copy unit (which can form a part of motion compensation unit 316), an affine unit, a linear model (LM) unit, etc. In other examples, video decoder 300 can include more, less, or different functional components.

[0170] CPB memory 320 can store video data to be decoded by components of video decoder 300, such as encoded video bitstreams. The video data stored in CPB memory 320 can be, for example, from computer-readable medium 110 (…). Figure 1 The CPB memory 320 may include a CPB that stores encoded video data (e.g., syntax elements) from the encoded video bitstream. Additionally, the CPB memory 320 may store video data other than the syntax elements of the decoded image, such as temporary data representing the output from various units of the video decoder 300. The DPB 314 typically stores decoded images that the video decoder 300 may output and / or use as reference video data when decoding subsequent data or images of the encoded video bitstream. The CPB memory 320 and DPB 314 may consist of any memory device from a variety of memory devices, such as DRAM, including SDRAM, MRAM, RRAM, or other types of memory devices. The CPB memory 320 and DPB 314 may be provided by the same memory device or separate memory devices. In various examples, the CPB memory 320 may be on-chip along with other components of the video decoder 300, or off-chip relative to those components.

[0171] Alternatively or concurrently, in some examples, the video decoder 300 can be derived from the memory 120 ( Figure 1 The decoded video data is retrieved. That is, memory 120 can utilize CPB memory 320 to store data as discussed above. Similarly, when some or all of the functions of video decoder 300 are implemented in software to be executed by the processing circuitry of video decoder 300, memory 120 can store instructions to be executed by video decoder 300.

[0172] exist Figure 4 The various units shown are illustrated to aid in understanding the operations performed by the video decoder 300. These units can be implemented as fixed-function circuits, programmable circuits, or a combination thereof. Similar to... Figure 3Fixed function circuits refer to circuits that provide specific functionality and are preset according to operations that can be performed. Programmable circuits refer to circuits that can be programmed to perform various tasks and provide flexible functionality in terms of operations that can be performed. For example, programmable circuits can execute software or firmware that cause the programmable circuits to function in a manner defined by instructions of the software or firmware. Fixed function circuits can 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 can be distinct circuit blocks (fixed function or programmable), and in some examples, one or more of the units can be integrated circuits.

[0173] Video decoder 300 can include ALUs, EFUs, digital circuits, analog circuits, and / or programmable cores made of programmable circuitry. In examples where operations of video decoder 300 are performed by software executing on programmable circuitry, on-chip or off-chip memory can store instructions (e.g., object code) of the software that video decoder 300 receives and executes.

[0174] Entropy decoding unit 302 can receive encoded video data from a CPB and entropy decode the video data to reproduce syntax elements. Prediction processing unit 304, inverse quantization unit 306, inverse transform processing unit 308, reconstruction unit 310, and filter unit 312 can generate decoded video data based on the syntax elements extracted from the bitstream.

[0175] In general, video decoder 300 reconstructs pictures on a block-by-block basis. Video decoder 300 can perform reconstruction operations separately on each block, where the block that is currently being reconstructed (i.e., decoded) can be referred to as the “current block.”

[0176] Entropy decoding unit 302 can entropy decode syntax elements defining quantized transform coefficients of a quantized transform coefficient block, as well as transform information such as a quantization parameter (QP) and / or an indication of a transform mode. Inverse quantization unit 306 can use the QP associated with the quantized transform coefficient block to determine a degree of quantization and, likewise, a degree of inverse quantization for inverse quantization unit 306 to apply. Inverse quantization unit 306 may, for example, perform a bit- shift operation to inverse quantize the quantized transform coefficients. Inverse quantization unit 306 may

[0177] After inverse quantization unit 306 forms a transform coefficient block, inverse transform processing unit 308 can 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 308 can 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.

[0178] Furthermore, prediction processing unit 304 generates a prediction block from the prediction information syntax elements entropy decoded by entropy decoding unit 302. For example, if the prediction information syntax elements indicate that the current block is inter predicted, motion compensation unit 316 can generate the prediction block. In this case, the prediction information syntax elements can indicate a reference picture in DPB 314 from which to retrieve a reference block, and a motion vector that identifies a position of the reference block in the reference picture relative to a position of the current block in the current picture. Motion compensation unit 316 can generally perform the inter prediction process in a manner substantially similar to that described with respect to motion compensation unit 224 Figure 3 ) with some exceptions.

[0179] As another example, if the prediction information syntax elements indicate that the current block is intra predicted, intra prediction unit 318 can generate the prediction block according to an intra prediction mode indicated by the prediction information syntax elements. Again, intra prediction unit 318 can generally perform the intra prediction process in a manner substantially similar to that described with respect to intra prediction unit 226 Figure 3 ) with some exceptions. Intra prediction unit 318 can retrieve data for neighboring samples of the current block from DPB 314.

[0180] Reconstruction unit 310 can use the prediction block and the residual block to reconstruct the current block. For example, reconstruction unit 310 can add samples of the residual block to corresponding samples of the prediction block to reconstruct the current block.

[0181] Filter unit 312 can perform one or more filter operations on the reconstructed block. For example, filter unit 312 can perform a deblocking operation to reduce blocking artifact pseudo-ghosts along edges of the reconstructed block. The operations of filter unit 312 are not necessarily performed in all examples.

[0182] Video decoder 300 can store the reconstructed blocks in DPB 314. For instance, in examples where operations of filter unit 312 are not performed, reconstruction unit 310 can store the reconstructed blocks to DPB 314. In examples where operations of filter unit 312 are performed, filter unit 312 can store the filtered reconstructed blocks to DPB 314. As discussed above, DPB 314 can provide reference information, such as samples of a current picture for intra prediction and samples of previously decoded pictures for subsequent motion compensation, to prediction processing unit 304. Moreover, video decoder 300 can output decoded pictures (e.g., decoded video) from DPB 314 for subsequent presentation on a display device, such as display device 118 of FIG. 1. Figure 1

[0183] The above describes example techniques for inter prediction and intra prediction. In one or more examples, video decoder 300 can be configured to perform palette mode coding, as described above. For instance, as shown, video decoder 300 can include palette mode unit 319. In one or more examples, palette mode unit 319 can be configured to determine a number of color components for palette mode decoding of a current block (e.g., palette mode unit 319 can determine a value for numComps based on numComps = (treeType == SINGLE_TREE)? (ChromaArrayType == 0? 1 : 3) : (treeType == DUAL_TREE_CHROMA)? 2 : 1.

[0184] For instance, based on syntax elements signaled by video encoder 200 and received from entropy decoding unit 302, prediction processing unit 304 can determine that a current block of video data is coded in palette mode. Prediction processing unit 304 can determine between single tree partitioning or dual tree partitioning whether the current block is coded with single tree partitioning or dual tree partitioning enabled. For instance, prediction processing unit 304 can receive syntax elements signaled by video encoder 200 that indicate whether single tree partitioning or dual tree partitioning is enabled. In some examples, prediction processing unit 304 can determine between single tree partitioning or dual tree partitioning that the current block is coded with single tree partitioning enabled (e.g., determine that treeType is equal to SINGLE_TREE).

[0185] ​The prediction processing unit 304 can determine that the current block is coded in a monochrome format (e.g., based on a value of ChromaArrayType). As one example, in response to determining that the current block is coded with single tree partitioning enabled, the prediction processing unit 304 can determine whether the current block is coded in a monochrome format. For example, in response to treeType being equal to SINGLE_TREE, the prediction processing unit 304 can determine whether ChromaArrayType is equal to 0. When the current block is coded with single tree partitioning enabled and when the current block is coded in a monochrome format, the prediction processing unit 304 can determine that a number of color components used for palette mode decoding of the current block is equal to one (e.g., numComps is equal to 1).

[0186] That is, in response to determining that the current block is coded with single tree partitioning enabled, the prediction processing unit 304 can determine that the current block is coded in a monochrome format. Further, in response to determining that the current block is coded with single tree partitioning enabled and in response to determining that the current block is coded in a monochrome format, the prediction processing unit 304 can determine that a number of color components used for palette mode decoding is equal to one.

[0187] In one or more examples, the prediction processing unit 304 can be configured to perform operations defined in a palette mode coding syntax structure. One non-limiting example of a palette mode coding syntax structure is the 7.3.9.6 palette coding syntax structure described above. When the current block is coded with single tree partitioning enabled and when the current block is coded in a monochrome, as part of performing operations defined in the palette mode coding syntax structure, the prediction processing unit 304 can be configured to determine that a number of color components used for palette mode decoding of the current block is equal to one.

[0188] Palette pattern unit 319 can be configured to perform palette pattern decoding on the current block based on the number of color components used for palette pattern decoding of the current block being equal to one. For example, palette pattern unit 319 can decode the current block based on a palette pattern table used only for the luminance component. In some examples, video encoder 200 can signal information for the palette pattern table (such as sample values ​​of the palette pattern table), and palette pattern unit 319 can construct the palette pattern table using the sample values. In this example, since the current block is decoded in monochrome format, only luminance sample values ​​may exist in the palette pattern table. In one or more examples, palette pattern unit 319 can receive an index of the palette pattern table for samples in the current block and assign luminance values ​​to samples in the current block based on the index of the palette pattern table.

[0189] In the example above, the current block can be considered the first block. In some examples, the prediction processing unit 304 can determine that the second block is decoded in palette mode, and determine whether the second block is decoded with single-tree partitioning enabled, between single-tree partitioning and dual-tree partitioning.

[0190] In this example, assume that prediction processing unit 304 determines that the second block is not decoded in monochrome format (e.g., ChromaArrayType is not equal to 0). When the second block is decoded with single-tree partitioning enabled and when the second block is not decoded in monochrome format, prediction processing unit 304 can determine that the number of color components used for palette mode decoding of the second block is equal to three (e.g., numComps equals three, because numComps = (treeType == SINGLE_TREE)?). <add>ChromaArrayType == 0? 1< / add> :3):(treeType==DUAL_TREE_CHROMA)? In 2:1, treeType is SINGLE_TREE and ChromaArrayType is not 0)

[0191] Then, the palette pattern unit 319 can perform palette pattern decoding on the second block based on the fact that the number of color components used for palette pattern decoding of the second block is three. For example, in this example, the palette pattern table may include sample values ​​for the luminance and chrominance components, since there are three color components.

[0192] In this way, video decoder 300 represents an example of a video decoding device that includes a memory configured to store video data and one or more processing units implemented in circuitry and configured to determine that one or more blocks are for monochrome content and decode the one or more blocks with a palette mode. In some examples, to determine that the one or more blocks are for monochrome content (e.g., include or contain monochrome content), the processing unit can be configured to determine (e.g., receive) a value of a chroma format (e.g., chroma format idc), where the value indicates that the one or more blocks are for monochrome content. In some examples, to determine that the one or more blocks are for monochrome content, the processing unit can determine a value of a separate color plane flag, where the value indicates that each color plane is coded as monochrome content, and where at least one color plane includes the one or more blocks. In some examples, the processing unit can be configured to determine that the one or more blocks are for separate color plane coding (e.g., include or contain separate color plane coding) and decode the one or more blocks with a palette mode. In some examples, the processing unit can be configured to determine a number of color components for the palette mode based on at least one of a tree type or a chroma format.

[0193] Figure 5 is a flowchart showing an example method for encoding a current block. The current block can include a current CU. Figure 5 Examples of are described with reference to a memory (examples of which include memory 120, CPB memory 320, DPB 314, or some other memory) and processing circuitry (examples of which include video decoder 300 and components of video decoder 300). For example, Figure 5 Examples of are described with reference to a memory (examples of which include memory 120, CPB memory 320, DPB 314, or some other memory) and processing circuitry (examples of which include video decoder 300 and components of video decoder 300). For example,

[0194] For example, the processing circuitry can determine that a current block of video data is coded with a palette mode (500) (e.g., based on signaled information). The processing circuitry can also determine between a single tree partitioning or a dual tree partitioning that the current block is coded with the single tree partitioning enabled (502) (e.g., based on signaled information).

[0195] The processing circuitry can determine that the current block is coded in a monochrome format (504). As one example, in response to determining that the current block is coded with single tree partitioning enabled, the processing circuitry can determine that the current block is coded in a monochrome format. For example, in response to determining that treeType is equal to SINGLE_TREE, the processing circuitry can determine whether ChromaArrayType is equal to 0, and in this example, the processing circuitry can determine that the current block is coded in a monochrome format (e.g., ChromaArrayType is equal to 0).

[0196] The processing circuitry can determine that the number of color components used for palette mode decoding of the current block is equal to one when the current block is coded with single tree partitioning enabled and when the current block is coded in a monochrome format (506). For example, in response to determining that the current block is coded with single tree partitioning enabled and in response to determining that the current block is coded in a monochrome format, the processing circuitry can determine that the number of color components used for palette mode decoding is equal to one.

[0197] As one example, the processing circuitry can be configured to perform operations defined in a palette mode coding syntax structure. In such an example, to determine that the number of color components used for palette mode decoding of the current block is equal to one, as part of performing the operations defined in the palette mode coding syntax structure, the processing circuitry can be configured to determine that the number of color components used for palette mode decoding of the current block is equal to one. For example, the operations defined by the palette mode coding syntax structure can include a determination of numComps, which is numComps = (treeType == SINGLE_TREE)? (ChromaArrayType == 0? 1 : 3) : (treeType == DUAL_TREE_CHROMA)? 2 : 1. In the formula for numComps, if treeType is SINGLE_TREE (e.g., single tree partitioning enabled) and if ChromaArrayType is 0 (e.g., monochrome format), then numComps is equal to 1.

[0198] The processing circuitry can be configured to perform palette mode decoding of the current block based on the determined number of color components used for palette mode decoding of the current block being equal to one (508). For example, the processing circuitry can perform palette mode decoding of the current block based on a palette mode table for only luma components. As one example, the processing circuitry can receive an index for a sample in the current block with respect to the palette mode table, and assign a luma value to the sample in the current block based on the index with respect to the palette mode table.

[0199] In the above example, treeType is SINGLE_TREE (e.g., single tree partitioning is enabled) and ChromaArrayType is 0 (e.g., monochrome format), and for this case, numComps is equal to 1. However, in some examples, for a second block coded in palette mode and in the single tree partitioning mode enabled case, the processing circuitry can determine that the second block is not coded in monochrome format (e.g., ChromaArrayType is not equal to 0).

[0200] In this case, when the second block is coded in the single tree partitioning enabled case and when the second block is not coded in monochrome format, the processing circuitry can determine that the number of color components used for palette mode decoding of the second block is equal to three. For example, numComps = (treeType == SINGLE_TREE)? (ChromaArrayType == 0? 1 : 3) : (treeType == DUAL_TREE_CHROMA)? 2 : 1. Accordingly, if treeType is SINGLE_TREE, but ChromaArrayType is not equal to 0, then numComps is equal to 3.

[0201] The processing circuitry can perform palette mode decoding of the second block based on the determined number of color components used for palette mode decoding of the second block being equal to three. For example, the palette mode table can include sample values for luma and chroma components, rather than only luma components as can be for monochrome format.

[0202] Figure 6 is a flowchart illustrating example techniques described in the disclosure. Figure 6 is described with respect to processing circuitry, examples of which include video encoder 200 or video decoder 300. Figure 6 The manner in which the processing circuitry can determine the number of color components used for palette mode decoding according to numComps = (treeType == SINGLE_TREE)? (ChromaArrayType == 0? 1 : 3) : (treeType == DUAL_TREE_CHROMA)? 2 : 1 is described.

[0203] The processing circuitry can determine (600) whether single tree partitioning is enabled for the current block (602) (e.g., determine whether treeType == SINGLE_TREE is true). In response to determining that single tree partitioning is enabled for the current block (602 is true), the processing circuitry can determine whether the current block is coded in a monochrome format (604) (e.g., whether ChromaArrayType is equal to 0).

[0204] In response to determining that the current block is coded in a monochrome format (604 is true), the processing circuitry can determine numComps = 1, which can mean that the processing circuitry can determine that the number of color components used for palette mode coding of the current block is equal to one when the current block is coded with single tree partitioning enabled and when the current block is coded in a monochrome format. In response to determining that the current block is not coded in a monochrome format (604 is false), the processing circuitry can determine numComps = 3, which can mean that the processing circuitry can determine that the number of color components used for palette mode coding of the current block is equal to three when the current block is coded with single tree partitioning enabled and when the current block is not coded in a monochrome format.

[0205] In response to determining that the current block is not coded with single tree partitioning (e.g., dual tree partitioning is enabled) (602 is false), the processing circuitry can determine whether a chroma component or a luma component is being processed (610). In response to determining that a chroma component is being processed (610 is true), the processing circuitry can determine numComps = 2 (612). In this example, numComps is equal to two because there are two color components (e.g., Cb and Cr). In response to determining that a chroma component is not being processed (610 is false), which means a luma component is being processed, the processing circuitry can determine numComps = 1. In this example, numComps is equal to one because there is only the luma component being processed (614).

[0206] The techniques described below as clauses can be performed together or in any combination. Example techniques should not be considered to be limited to the clauses below.

[0207] Clause 1. A method of coding video data, the method comprising: determining that one or more blocks of video data are for monochrome content; and coding the one or more blocks with a palette mode.

[0208] Clause 2. The method of clause 1, wherein determining that the one or more blocks are for monochrome content comprises: determining a value of a chroma format, wherein the value indicates that the one or more blocks are for monochrome content.

[0209] Clause 3. The method of clause 1, wherein determining that the one or more blocks are for monochrome content comprises determining a value of a separate color plane flag, wherein the value indicates that each color plane of a plurality of color planes is coded as monochrome content, and wherein at least one of the color planes comprises the one or more blocks.

[0210] Clause 4. A method of coding video data, the method comprising: determining that one or more blocks of video data are for separate color plane coding; and coding the one or more blocks with a palette mode.

[0211] Clause 5. The method of any of clauses 1-4, further comprising determining a number of color components for the palette mode based on at least one of a tree type or a chroma format.

[0212] Clause 6. The method of any one or combination of clauses 1-5.

[0213] Clause 7. The method of any of clauses 1-6, wherein coding comprises decoding.

[0214] Clause 8. The method of any of clauses 1-6, wherein coding comprises encoding.

[0215] Clause 9. An apparatus for coding video data, the apparatus comprising: a memory configured to store video data; and a processing circuit coupled to the memory and configured to perform the method of any one or combination of clauses 1-8.

[0216] Clause 10. The apparatus of clause 9, further comprising: a display configured to display decoded video data.

[0217] Clause 11. The apparatus of any of clauses 9 and 10, wherein the apparatus comprises one or more of: a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

[0218] Clause 12. The apparatus of any of clauses 9-11, wherein the apparatus comprises a video decoder.

[0219] Clause 13. The apparatus of any of clauses 9-11, wherein the apparatus comprises a video encoder.

[0220] Clause 14. A computer-readable storage medium having stored thereon instructions that, when executed, cause one or more processors to perform the method of any of clauses 1-8.

[0221] Clause 15. An apparatus for coding video data, the apparatus comprising means for performing the method of any one or any combination of clauses 1-8.

[0222] It is recognized that, in accordance with examples, certain acts or events of any of the techniques described herein can be performed in a different sequence, can be added, merged, or omitted altogether (for example, not all described acts or events are necessary for the practice of the techniques). Moreover, in certain examples, acts or events can be performed concurrently, for example, through multi-threaded processing, interrupt processing, or multiple processors, rather than sequentially.

[0223] In one or more examples, the functions described can be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions can be stored on or transmitted over as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media can include computer-readable storage media, which corresponds to a tangible medium such as data storage media, or communication media including any medium that facilitates transfer of a computer program from one place to another, e.g., according to a communication protocol. In this manner, computer- readable media generally can correspond to (1) tangible computer-readable storage media which is non-transitory or (2) a communication medium such as a signal or carrier wave. Data storage media can be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, code, and / or data structures for implementation of the techniques described in this disclosure. A computer program product can include a computer-readable medium.

[0224] By way of example, and not limitation, such computer-readable storage media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage, or other magnetic storage devices, flash memory, or any other storage medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any

[0225] Instructions can 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, as used herein the term "processor" and "processing circuitry" can refer to any of the foregoing structures or any other structure suitable for implementation of the techniques described herein. In addition, in some aspects, the functionality described herein can be provided within dedicated hardware and / or software modules configured for encoding and decoding, or incorporated in a combined codec. Also, the techniques could be fully implemented in one or more circuits or logic elements.

[0226] The techniques of this disclosure can be implemented in a wide variety of devices or apparatuses, including a wireless handset, an integrated circuit (IC) or a set of ICs (e.g., a chip set). Various components, modules, or units are described herein as being stored in or on memory, which can include one or more types of computer-readable storage media. In some examples, a component, module, or unit can be a software module or firmware module operating to

[0227] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

1. A method for decoding video data, the method comprising: It is determined that the current block of the video data is decoded in palette mode; Determine whether the current block is being decoded with single-tree partitioning enabled, or with dual-tree partitioning. It is determined that the current block is decoded in monochrome format; When the current block is decoded with single-tree partitioning enabled and when the current block is decoded in monochrome format, the number of color components used for palette mode decoding of the current block is determined to be equal to one. as well as The current block is decoded in a palette mode based on the fact that the number of color components used for palette mode decoding is equal to one.

2. The method according to claim 1, wherein, Determining that the current block is decoded in monochrome format includes: In response to determining that the current block is being decoded with single-tree partitioning enabled, it is determined that the current block is being decoded in monochrome format.

3. The method according to claim 1, further comprising: Perform the operations defined in the palette mode decoding syntax structure. Specifically, determining that the number of color components used for palette mode decoding of the current block is equal to one includes: as part of performing an operation defined in the palette mode decoding syntax structure, determining that the number of color components used for palette mode decoding of the current block is equal to one.

4. The method according to claim 1, wherein, The current block is the first block, and the method further includes: It was determined that the second block was decoded using a palette mode; The second block is determined to be decoded when single-tree partitioning is enabled, between single-tree partitioning and dual-tree partitioning. It was determined that the second block was not decoded in monochrome format; When the second block is decoded with single-tree partitioning enabled and when the second block is not decoded in monochrome format, the number of color components used for palette mode decoding of the second block is determined to be equal to three; and The second block is decoded in a palette mode based on the fact that the number of color components used for palette mode decoding is three.

5. The method according to claim 1, wherein, Palette mode decoding of the current block includes: performing palette mode decoding of the current block based on a palette mode table used only for the luminance component.

6. The method according to claim 5, wherein, Decoding the current block based on the palette pattern table includes: Receive an index of the sample in the current block regarding the palette pattern table; and A brightness value is assigned to the sample in the current block based on the index of the palette pattern table.

7. An apparatus for decoding video data, the apparatus comprising: A memory configured to store the video data; as well as Processing circuitry, coupled to the memory, is configured to: It is determined that the current block of the video data is decoded in palette mode; Determine whether the current block is being decoded with single-tree partitioning enabled, or with dual-tree partitioning. It is determined that the current block is decoded in monochrome format; When the current block is decoded with single-tree partitioning enabled and when the current block is decoded in monochrome format, the number of color components used for palette mode decoding of the current block is determined to be equal to one. as well as The current block is decoded in a palette mode based on the fact that the number of color components used for palette mode decoding is equal to one.

8. The device according to claim 7, wherein, To determine that the current block is decoded in monochrome format, the processing circuit is configured as follows: In response to determining that the current block is being decoded with single-tree partitioning enabled, it is determined that the current block is being decoded in monochrome format.

9. The device according to claim 7, wherein, The processing circuit is configured as follows: Perform the operations defined in the palette mode decoding syntax structure. In order to determine that the number of color components used for palette mode decoding of the current block is equal to one, the processing circuit is configured to determine that the number of color components used for palette mode decoding of the current block is equal to one as part of performing operations defined in the palette mode decoding syntax structure.

10. The device according to claim 7, wherein, The current block is the first block, and the processing circuit is configured to: It was determined that the second block was decoded using a palette mode; The second block is determined to be decoded when single-tree partitioning is enabled, between single-tree partitioning and dual-tree partitioning. It was determined that the second block was not decoded in monochrome format; When the second block is decoded with single-tree partitioning enabled and when the second block is not decoded in monochrome format, the number of color components used for palette mode decoding of the second block is determined to be equal to three; and The second block is decoded in a palette mode based on the fact that the number of color components used for palette mode decoding is three.

11. The device according to claim 7, wherein, In order to perform palette mode decoding on the current block, the processing circuit is configured to perform palette mode decoding on the current block based on a palette mode table used only for the luminance component.

12. The device according to claim 11, wherein, In order to perform palette pattern decoding on the current block based on the palette pattern table, the processing circuit is configured as follows: Receive an index of the sample in the current block regarding the palette pattern table; and A brightness value is assigned to the sample in the current block based on the index of the palette pattern table.

13. The device according to claim 7, further comprising: A display configured to show decoded video data.

14. The device according to claim 7, wherein, The device includes one or more of the following: a camera, a computer, a mobile device, a broadcast receiver, or a set-top box.

15. A computer-readable storage medium having instructions stored thereon, said instructions, when executed, causing one or more processors to perform the following operations: It is determined that the current block of video data is decoded in palette mode; Determine whether the current block is being decoded with single-tree partitioning enabled, or with dual-tree partitioning. It is determined that the current block is decoded in monochrome format; When the current block is decoded with single-tree partitioning enabled and when the current block is decoded in monochrome format, the number of color components used for palette mode decoding of the current block is determined to be equal to one. as well as The current block is decoded in a palette mode based on the fact that the number of color components used for palette mode decoding is equal to one.

16. An apparatus for decoding video data, the apparatus comprising: A unit for determining whether the current block of the video data is decoded in palette mode; A unit used to determine whether the current block is being decoded with single-tree partitioning enabled, or dual-tree partitioning; A unit used to determine whether the current block is decoded in monochrome format; A unit for determining that the number of color components used for palette mode decoding of the current block is equal to one when the current block is decoded with single-tree partitioning enabled and when the current block is decoded in monochrome format. as well as A unit for performing palette mode decoding on the current block based on the fact that the number of color components used for palette mode decoding of the current block is equal to one.

17. The device according to claim 16, wherein, The unit for determining that the current block is decoded in monochrome format includes: A unit for determining, in response to determining that the current block is being decoded with single-tree partitioning enabled, that the current block is being decoded in monochrome format.

18. The device according to claim 16, further comprising: Units used to perform operations defined in the palette mode decoding syntax structure. The unit for determining that the number of color components used for palette mode decoding of the current block is equal to one includes: a unit for determining that the number of color components used for palette mode decoding of the current block is equal to one as part of performing an operation defined in the palette mode decoding syntax structure.

19. The device according to claim 16, wherein, The current block is the first block, and the device further includes: Used to determine that the second block is a unit decoded in palette mode; Used to determine whether the second block is a unit for decoding when single-tree partitioning is enabled, between single-tree partitioning and dual-tree partitioning; Used to determine that the second block is not decoded in monochrome format; A unit for determining that the number of color components used for palette mode decoding of the second block is equal to three, when the second block is decoded with single-tree partitioning enabled and when the second block is not decoded in monochrome format; and A unit for performing palette mode decoding on the second block based on the determined number of color components used for palette mode decoding of the second block being equal to three.

20. The device according to claim 16, wherein, The unit for performing palette mode decoding on the current block includes: a unit for performing palette mode decoding on the current block based on a palette mode table used only for the luminance component.

21. The device according to claim 20, wherein, The unit for performing palette pattern decoding on the current block based on the palette pattern table includes: A unit for receiving an index of the sample in the current block regarding the palette pattern table; and A unit for assigning brightness values ​​to the samples in the current block based on the index of the palette pattern table.

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