Chroma intra prediction unit for video coding

Abstract

A video decoder may be configured to: determine that a block of video data is formatted according to a 4:4:4 video coding format; determine that the block of video data is encoded in an intra-prediction mode; determine to disable a minimum chroma intra prediction unit (SCIPU) for the block in response to determining that the block has a 4:4:4 video coding format; decode the block of video data based on the determination to disable the SCIPU; and output decoded video data comprising a decoded version of the block.

Description

[0001] This application claims priority from the following applications:

[0002] U.S. patent application No. 16 / 947,489, filed on August 4, 2020, claims the benefits of:

[0003] U.S. Provisional Application No. 62 / 882,995, filed on August 5, 2019;

[0004] U.S. Provisional Application No. 62 / 885,069, filed on August 9, 2019;

[0005] U.S. Provisional Application No. 62 / 889,378, filed on August 20, 2019; and

[0006] U.S. Provisional Application No. 62 / 902,188, filed September 18, 2019;

[0007] The entire contents of each of the above applications are incorporated herein by reference. Technical Field

[0008] This disclosure relates to video encoding and video decoding. Background Art

[0009] Digital video capabilities may be incorporated into a wide variety of devices, including digital televisions, digital live 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 gaming consoles, cellular or satellite radio telephones (so-called "smartphones"), 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. By implementing such video coding techniques, video devices may more efficiently transmit, receive, encode, decode, and / or store digital video information.

[0010] Video coding techniques include spatial (intra-picture) prediction and / or temporal (inter-picture) prediction to reduce or remove redundancy inherent in video sequences. For block-based video coding, a video slice (e.g., a video picture or a portion of a video picture) may be partitioned into video blocks, which may also be referred to as coding tree units (CTUs), coding units (CUs), and / or coding nodes. Video blocks in an intra-coded (I) slice of a picture are encoded using spatial prediction relative to reference samples in neighboring blocks in the same picture. Video blocks in an inter-coded (P or B) slice of a picture may use spatial prediction relative to reference samples in neighboring blocks in the same picture or temporal prediction relative to reference samples in other reference pictures. Pictures may be referred to as frames, and reference pictures may be referred to as reference frames. Summary of the Invention

[0011] In summary, this disclosure describes techniques for chroma intra prediction units, such as example techniques for extending a minimum chroma intra prediction unit. The example techniques can be used with the Versatile Video Coding (VVC) standard, the High Efficiency Video Coding (HEVC) standard, or other video coding standards. The example techniques are not limited to video coding standards and can be applicable to video coding in general.

[0012] According to one example, a method includes determining that a block of video data is formatted according to a 4:4:4 video coding format; determining that the block of video data is encoded in an intra-prediction mode; in response to determining that the block has the 4:4:4 video coding format, determining to disable a minimum chroma intra prediction unit (SCIPU) for the block; decoding the block of video data based on the determination to disable the SCIPU; and outputting decoded video data including a decoded version of the block.

[0013] According to another example, a device for decoding video data includes: a memory configured to store video data; and one or more processors implemented in a circuit and configured to: determine that a block of the video data is formatted according to a 4:4:4 video coding format; determine that the block of the video data is encoded in an intra-frame prediction mode; in response to determining that the block has the 4:4:4 video coding format, determine to disable a minimum chroma intra-frame prediction unit (SCIPU) for the block; decode the block of the video data based on the determination to disable the SCIPU; and output decoded video data including a decoded version of the block.

[0014] According to another example, a computer-readable storage medium stores instructions that, when executed by one or more processors, cause the one or more processors to perform the following operations: determine that a block of video data is formatted according to a 4:4:4 video coding format; determine that the block of video data is encoded in an intra-frame prediction mode; in response to determining that the block has the 4:4:4 video coding format, determine to disable a minimum chroma intra-frame prediction unit (SCIPU) for the block; decode the block of video data based on the determination to disable the SCIPU; and output decoded video data including a decoded version of the block.

[0015] According to another example, a device for decoding video data includes: a unit for determining that a block of the video data is formatted according to a 4:4:4 video coding format; a unit for determining that the block of the video data is encoded in an intra-frame prediction mode; a unit for determining to disable a minimum chroma intra-frame prediction unit (SCIPU) for the block in response to determining that the block has the 4:4:4 video coding format; a unit for decoding the block of the video data based on the determination regarding disabling the SCIPU; and a unit for outputting decoded video data including a decoded version of the block.

[0016] 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 THE DRAWINGS

[0017] Figure 1 is a block diagram illustrating an example video encoding and decoding system that may perform the techniques of this disclosure.

[0018] Figure 2A and Figure 2B is a conceptual diagram illustrating an example quadtree binary tree (QTBT) structure and a corresponding coding tree unit (CTU).

[0019] Figure 3A – 3E is a conceptual diagram illustrating an example of a multi-type tree splitting pattern.

[0020] Figure 4 is a conceptual diagram illustrating an example of the direction of intra prediction, where arrows point to reference samples.

[0021] Figure 5 is a conceptual diagram illustrating an example of an intra-predicted 8x4 rectangular block.

[0022] Figures 6A-6C is a conceptual diagram illustrating a mode mapping process for modes outside the range of a diagonal direction.

[0023] Figure 7 is a conceptual diagram showing wide angles (-1 to -10 and 67 to 76) in addition to the 65 angle modes.

[0024] Figure 8 is a conceptual diagram showing wide angles (-1 to -14 and 67 to 80) in addition to modes 2 and 6, for a total of 93 angle modes.

[0025] Figure 9 is a mapping table used to determine the angle used for intra prediction.

[0026] Figure 10 is a conceptual diagram illustrating an example of adjacent samples used for intra prediction.

[0027] Figure 11A and 11B is a conceptual diagram illustrating an example of a minimum chroma intra prediction unit (SCIPU).

[0028] Figures 12A-12S is a conceptual diagram illustrating additional examples of SCIPUs.

[0029] Figure 13 is a conceptual diagram illustrating an example of a luminance region.

[0030] Figures 14A-14C is shown for different chroma formats Figure 13 Conceptual diagram of an example of corresponding chrominance areas of a luminance area.

[0031] Figure 15 is a block diagram illustrating an example video encoder that may perform the techniques of this disclosure.

[0032] Figure 16 is a block diagram illustrating an example video decoder that may perform the techniques of this disclosure.

[0033] Figure 17 is a flowchart illustrating an example method for encoding a current block.

[0034] Figure 18 is a flow chart illustrating an example method for decoding a current block.

[0035] Figure 19 is a flow chart illustrating an example method for decoding a current block. DETAILED DESCRIPTION

[0036] This disclosure describes techniques related to the operation of a video coder (e.g., a video encoder and / or a video decoder). Video coding (e.g., video encoding and / or video decoding) typically involves predicting a block of video data based on already coded video data blocks in the same picture (e.g., intra-frame prediction) or predicting a block of video data based on already coded video data blocks in different pictures (e.g., inter-frame prediction). In some cases, the video encoder also calculates residual data by comparing the predicted block with the original block. Thus, the residual data represents the difference between the predicted block and the original block. To reduce the number of bits required to signal the residual data, the video encoder transforms and quantizes the residual data and signals the transformed and quantized residual data in the coded bitstream. The compression achieved by the transform and quantization process may be lossy, meaning that the transform and quantization process may introduce distortion into the decoded video data.

[0037] The video decoder decodes the residual data and adds it to the prediction block to produce a reconstructed video block that more closely matches the original video block than the prediction block alone. Due to losses introduced by the transformation and quantization of the residual data, the first reconstructed block may have distortion or artifacts. A common type of artifact or distortion is called blocking, in which the boundaries of the blocks used to decode the video data are visible.

[0038] To further improve the quality of the decoded video, the video decoder may perform one or more filtering operations on the reconstructed video blocks. Examples of these filtering operations include deblocking filtering, sample adaptive offset (SAO) filtering, and adaptive loop filtering (ALF). The parameters for these filtering operations may be determined by the video encoder and explicitly signaled in the coded video bitstream, or may be implicitly determined by the video decoder without explicitly signaling these parameters in the coded video bitstream.

[0039] In general, the techniques of the present disclosure relate to intra-frame prediction. More specifically, the techniques of the present disclosure relate to a minimum chroma intra prediction unit (SCIPU). In a typical video decoder, especially a hardware-based video decoder, small blocks reduce processing throughput compared to larger blocks. This reduction in processing throughput is primarily caused by small intra-frame predicted blocks because, unlike small inter-frame predicted blocks, small intra-frame predicted blocks cannot be processed in parallel due to data dependencies between adjacent blocks. For example, in order to generate a prediction block for an intra-frame predicted block, the video decoder needs to have decoded the top and left boundary reconstructed samples from adjacent blocks, thereby requiring the intra-frame predicted block to be processed sequentially with the adjacent blocks rather than in parallel.

[0040] To improve worst-case processing throughput in the emerging Versatile Video Coding (VVC) standard, SCIPU is employed. SCIPU disables intra-chroma CBs that are smaller than 16 chroma samples by constraining the splitting of intra-chroma CBs. However, existing techniques for implementing SCIPU may prevent the use of smaller chroma blocks in some decoding scenarios where the use of smaller chroma blocks can improve decoding performance. For example, in a 4:4:4 video format, the luma component and the chroma components have the same size, and there are no 2x2, 4x2, or 2x4 chroma blocks. Therefore, implementing SCIPU constraints for such videos unnecessarily limits the splitting options for 4:4:4 videos, including certain types of small blocks, which may degrade decoding quality. By determining to disable the SCIPU constraint for a block in response to determining that the block has a 4:4:4 video decoding format, the techniques of the present disclosure may advantageously enable video encoders and video decoders to disable SCIPU in decoding scenarios where smaller blocks can produce better decoding performance. According to the techniques of the present disclosure, the video decoder can still determine to enable SCIPU for the second block in response to determining that the second block has a non-4:4:4 video decoding format, thereby still reducing the worst-case complexity. As used in this disclosure, enabling SCIPU generally refers to setting the minimum allowed size of the block to the size of the SCIPU, and disabling SCIPU means not setting the minimum allowed size of the block to the size of the SCIPU, so that blocks smaller than the size of the SCIPU can be used.

[0041] Figure 1 is a block diagram illustrating an example video encoding and decoding system 100 that can perform the techniques of this disclosure. Generally speaking, the techniques of this disclosure relate to decoding (encoding and / or decoding) video data. Generally, video data includes any data used to process video. Thus, video data can include original, unencoded video, encoded video, decoded (e.g., reconstructed) video, and video metadata (e.g., signaling data).

[0042] like Figure 1As shown, in this example, system 100 includes a source device 102 that provides encoded video data to be decoded and displayed by a destination device 116. Specifically, source device 102 provides the video data to destination device 116 via a computer-readable medium 110. Source device 102 and destination device 116 may include any of a wide variety of devices, including desktop computers, notebook computers (i.e., laptop computers), mobile devices, tablet computers, set-top boxes, telephone handsets such as smartphones, televisions, cameras, display devices, digital media players, video game consoles, video streaming devices, broadcast receiver devices, etc. In some cases, source device 102 and destination device 116 may be equipped for wireless communication and, therefore, may be referred to as wireless communication devices.

[0043] exist Figure 1 In the example of , source device 102 includes video source 104, memory 106, video encoder 200, and output interface 108. Destination device 116 includes input interface 122, video decoder 300, memory 120, and display device 118. According to the present disclosure, the video encoder 200 of source device 102 and the video decoder 300 of destination device 116 can be configured to apply techniques for enabling and disabling SCIPU. Thus, source device 102 represents an example of a video encoding device, while destination device 116 represents an example of a video decoding device. In other examples, the source device and destination device can include other components or arrangements. For example, source device 102 can receive video data from an external video source such as an external camera. Similarly, destination device 116 can interface with an external display device rather than including an integrated display device.

[0044] like Figure 1 The illustrated system 100 is merely an example. In general, any digital video encoding and / or decoding device can implement the techniques described herein for enabling and disabling SCIPUs. Source device 102 and destination device 116 are merely examples of decoding devices, where source device 102 generates decoded video data for transmission to destination device 116. This disclosure refers to a "decoding" device as a device that performs decoding (e.g., encoding and / or decoding) of data. Thus, video encoder 200 and video decoder 300 represent examples of decoding devices (specifically, a video encoder and a video decoder, respectively). In some examples, source device 102 and destination device 116 can operate in a substantially symmetrical manner, such that each of source device 102 and destination 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 destination device 116, for example, for video streaming, video playback, video broadcasting, or video telephony.

[0045] Typically, video source 104 represents a source of video data (i.e., raw, unencoded video data) and provides a sequential series of pictures (also referred to as "frames") of video data to video encoder 200, which encodes the data for the pictures. Video source 104 of source device 102 may include a video capture device, such as a camera, a video archive unit containing previously captured raw video, and / or a video feed interface for receiving video from a video content provider. As another alternative, video source 104 may generate computer graphics-based data as source video, or a combination of real-time video, archived video, and computer-generated video. In each case, video encoder 200 may encode captured, pre-captured, or computer-generated video data. Video encoder 200 may rearrange the pictures from the order in which they were received (sometimes referred to as "display order") into a decoding order for decoding. Video encoder 200 may generate a bitstream comprising the encoded video data. Source device 102 may then output the encoded video data onto computer-readable medium 110 via output interface 108 to be received and / or retrieved by, for example, input interface 122 of destination device 116 .

[0046] Memory 106 of source device 102 and memory 120 of destination device 116 represent general purpose memory. In some examples, memories 106, 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, 120 can store software instructions executable by, for example, video encoder 200 and video decoder 300, respectively. Although memory 106 and memory 120 are shown in this example as separate from video encoder 200 and video decoder 300, it should be understood that video encoder 200 and video decoder 300 can also include internal memory for functionally similar or equivalent purposes. Furthermore, memories 106, 120 can store, for example, encoded video data output from video encoder 200 and input to video decoder 300. In some examples, portions of memories 106, 120 can be allocated as one or more video buffers, e.g., to store raw decoded and / or encoded video data.

[0047] The computer-readable medium 110 can represent any type of medium or device capable of transmitting encoded video data from the source device 102 to the destination device 116. In one example, the computer-readable medium 110 represents a communication medium that enables the source device 102 to send the encoded video data directly to the destination device 116 in real time, for example, via a radio frequency network or a computer-based network. The output interface 108 can modulate a transmission signal including the encoded video data according to a communication standard such as a wireless communication protocol, and the input interface 122 can demodulate the received transmission signal according to the communication standard. The communication medium can include 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 device that can be useful for facilitating communication from the source device 102 to the destination device 116.

[0048] In some examples, source device 102 may output the encoded data from output interface 108 to storage device 112. Similarly, destination device 116 may access the encoded data from storage device 112 via input interface 122. Storage device 112 may include any of a variety of distributed or locally accessed data storage media, such as a hard drive, Blu-ray disc, DVD, CD-ROM, flash memory, volatile or non-volatile memory, or any other suitable digital storage medium for storing encoded video data.

[0049] In some examples, source device 102 may output the encoded video data to file server 114 or another intermediate storage device that may store the encoded video data generated by source device 102. Destination device 116 may access the stored video data from file server 114 via streaming or downloading.

[0050] The file server 114 may be any type of server device capable of storing encoded video data and sending the encoded video data to the destination device 116. The file server 114 may represent a web server (e.g., for a website), a server configured to provide file transfer protocol services (such as the File Transfer Protocol (FTP) or the 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. The file server 114 may additionally or alternatively 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, etc.

[0051] The destination device 116 may access the encoded video data from the file server 114 through any standard data connection, including an Internet connection. This may include a wireless channel (e.g., a Wi-Fi connection), a wired connection (e.g., a digital subscriber line (DSL), a cable modem, etc.), or a combination of both, suitable for accessing the encoded video data stored on the file server 114. The input interface 122 may 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.

[0052] The output interface 108 and the input interface 122 may represent wireless transmitters / receivers, modems, wired networking components (e.g., Ethernet cards), wireless communication components that operate according to any of the various 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 may be configured to transmit data (such as encoded video data) according to a cellular communication standard (such as 4G, 4G-LTE (Long Term Evolution), Advanced LTE, 5G, etc.). In some examples where the output interface 108 includes a wireless transmitter, the output interface 108 and the input interface 122 may be configured to transmit data (such as encoded video data) according to other wireless standards (such as IEEE 802.11 specifications, IEEE 802.15 specifications (e.g., ZigBee 5G), etc.). TM ), Bluetooth TMStandards, etc.) to transmit data (such as encoded video data). In some examples, source device 102 and / or destination device 116 may include corresponding system-on-chip (SoC) devices. For example, source device 102 may include a SoC device for performing the functions assigned to video encoder 200 and / or output interface 108, and destination device 116 may include a SoC device for performing the functions assigned to video decoder 300 and / or input interface 122.

[0053] The techniques of the present disclosure can be applied to video decoding to support any of a variety of multimedia applications, such as over-the-air television broadcasting, cable television transmission, satellite television transmission, Internet streaming video transmission (such as Dynamic Adaptive Streaming over HTTP (DASH)), digital video encoded onto a data storage medium, decoding of digital video stored on a data storage medium, or other applications.

[0054] The input interface 122 of the destination device 116 receives an encoded video bitstream from the computer-readable medium 110 (e.g., a communication medium, a storage device 112, a file server 114, etc.). The encoded video bitstream may include signaling information such as syntax elements defined by the video encoder 200 (which are also used by the video decoder 300): the syntax elements have values ​​that describe the characteristics and / or processing of video blocks or other decoding units (e.g., slices, pictures, groups of pictures, sequences, etc.). The display device 118 displays the decoded pictures of the decoded video data to a user. The display device 118 may represent any of a variety of display devices, such as a liquid crystal display (LCD), a plasma display, an organic light emitting diode (OLED) display, or another type of display device.

[0055] Despite Figure 1 2. Although not shown, in some examples, the video encoder 200 and the video decoder 300 can each be integrated with an audio encoder and / or an audio decoder and can 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. If applicable, the MUX-DEMUX units can follow the ITU H.223 multiplexer protocol or other protocols such as the User Datagram Protocol (UDP).

[0056] The video encoder 200 and the video decoder 300 can each be implemented as any of a variety of suitable encoder and / or decoder circuits, 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 combination thereof. When the technology is partially implemented in software, the device can store instructions for the software in a suitable non-transitory computer-readable medium and, using one or more processors, execute the instructions in hardware to perform the technology of the present disclosure. Each of the video encoder 200 and the video decoder 300 can be included in one or more encoders or decoders, any of which can be integrated as part of a combined encoder / decoder (CODEC) in the corresponding device. The device including the video encoder 200 and / or the video decoder 300 can include an integrated circuit, a microprocessor, and / or a wireless communication device (such as a cellular phone).

[0057] The video encoder 200 and the video decoder 300 may operate in accordance with a video coding standard, such as the ITU-T H.265 standard (also known as the High Efficiency Video Coding (HEVC) standard) or an extension thereof, such as the multi-view and / or scalable video coding extensions. Alternatively, the video encoder 200 and the video decoder 300 may operate in accordance with other proprietary or industry standards, such as the ITU-T H.266 standard, also known as VVC. A draft of the VVC standard is described in the following document: Bross et al., “Versatile Video Coding (Draft 6)”, Joint Video Experts Team (JVET) of ITU-T SG 16WP 3 and ISO / IEC JTC 1 / SC 29 / WG 11, 15th Meeting: Gothenburg, Sweden, July 3-12, 2019, JVET-O2001-vE (hereinafter referred to as “VVC Draft 6”). Another draft of the VVC standard is described in the following document: Bross et al., "Versatile Video Coding (Draft 10)", Joint Video Experts Team (JVET) of ITU-T SG 16 WP 3 and ISO / IEC JTC 1 / SC 29 / WG11, 18th Meeting: by Teleconference, June 22-July 1, 2020, JVET-S2001-v16 (hereinafter referred to as "VVC Draft 10"). However, the techniques of this disclosure are not limited to any particular coding standard.

[0058] Typically, the video encoder 200 and video decoder 300 can perform block-based decoding of a picture. The term "block" generally refers to a structure that includes data to be processed (e.g., to be 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. Typically, the video encoder 200 and video decoder 300 can decode video data represented in a YUV (e.g., Y, Cb, Cr) format. That is, rather than decoding the red, green, and blue (RGB) data for samples of a picture, the video encoder 200 and video decoder 300 can decode luma and chroma components, where the chroma components can include both red and blue hue chroma components. In some examples, the video encoder 200 converts the received RGB formatted data to a YUV representation before encoding, and the video decoder 300 converts the YUV representation to an RGB format. Alternatively, a pre-processing unit and a post-processing unit (not shown) can perform these conversions.

[0059] In general, this disclosure may refer to the decoding of a picture (e.g., encoding and decoding) as a process that includes encoding or decoding the data of the picture. Similarly, this disclosure may refer to the decoding of a block of a picture as a process that includes encoding or decoding the data for the block (e.g., prediction and / or residual decoding). A coded video bitstream typically includes a series of values ​​for syntax elements that represent decoding decisions (e.g., decoding mode) and the partitioning of the picture into blocks. Therefore, references to decoding a picture or block should generally be understood as decoding the values ​​of the syntax elements used to form the picture or block.

[0060] HEVC defines various blocks, including coding units (CUs), prediction units (PUs), and transform units (TUs). According to HEVC, a video decoder (such as the video encoder 200) partitions a coding tree unit (CTU) into CUs according to a quadtree structure. That is, the video decoder partitions the CTU and CU into four equal, non-overlapping squares, and each node of the quadtree has zero or four child nodes. A node without child nodes may be referred to as a "leaf node," and the CU of such a leaf node may include one or more PUs and / or one or more TUs. The video decoder may further partition the PUs and TUs. For example, in HEVC, the residual quadtree (RQT) represents the partitioning of the TUs. In HEVC, PU represents inter-frame prediction data, and TU represents residual data. An intra-predicted CU includes intra-frame prediction information, such as an intra-frame mode indication.

[0061] As another example, the video encoder 200 and the video decoder 300 can be configured to operate according to VVC. According to VVC, a video decoder (such as the video encoder 200) partitions a picture into multiple CTUs. The video encoder 200 can partition the CTU according to a tree structure (such as a quadtree-binary tree (QTBT) structure or a multi-type tree (MTT) structure). The QTBT structure removes the concept of multiple partitioning types, such as the separation between CU, PU, ​​and TU in HEVC. The QTBT structure includes two levels: a first level partitioned according to quadtree partitioning, and a second level partitioned according to binary tree partitioning. The root node of the QTBT structure corresponds to the CTU. The leaf nodes of the binary tree correspond to decoding units (CUs).

[0062] In the MTT partitioning structure, blocks can be partitioned using quadtree (QT) partitioning, binary tree (BT) partitioning, and one or more types of ternary tree (TT) (also known as ternary tree (TT)) partitioning. A ternary tree or ternary tree partitioning is a partitioning in which a block is split into three sub-blocks. In some examples, the ternary tree or ternary tree partitioning divides the block into three sub-blocks without dividing the original block through the center. The partitioning types in MTT (e.g., QT, BT, and TT) can be symmetric or asymmetric.

[0063] In some examples, the video encoder 200 and the video decoder 300 may use a single QTBT or MTT structure to represent each of the luma component and the chroma components, while in other examples, the video encoder 200 and the video decoder 300 may use two or more QTBT or MTT structures, such as one QTBT / MTT structure for the luma component and another QTBT / MTT structure for the two chroma components (or two QTBT / MTT structures for the respective chroma components).

[0064] The video encoder 200 and the video decoder 300 can be configured to use quadtree segmentation, QTBT segmentation, MTT segmentation, or other segmentation structures according to HEVC. For the purpose of explanation, the technology of the present disclosure is described with respect to QTBT segmentation. However, it should be understood that the technology of the present disclosure can also be applied to video decoders configured to use quadtree segmentation or other types of segmentation.

[0065] In some examples, a CTU includes a coding tree block (CTB) of luma samples, two corresponding CTBs of chroma samples for a picture with three sample arrays, or a CTB of samples for a monochrome picture or a picture coded using three separate color planes and syntax structures for coding the samples. A CTB can be an NxN block of samples (for some value of N), such that dividing a component into a CTB is a partitioning. A component is an array or a single sample from one of the three arrays (one luma and two chroma) that make up a picture in 4:2:0, 4:2:2, or 4:4:4 color format, or an array or a single sample of an array that makes up a picture in monochrome format. In some examples, a coding block (CB) is an MxN block of samples (for some values ​​of M and N), such that dividing a CTB into CBs is a partitioning.

[0066] Blocks (e.g., CTUs or CUs) can be grouped in a picture in various ways. As an example, a brick can refer to a rectangular area of ​​a CTU row within a particular tile in a picture. A tile can be a rectangular area of ​​a CTU within a particular tile column and a particular tile row in a picture. A tile column refers to a rectangular area of ​​a CTU with a height equal to the height of the picture and a width specified by a syntax element (e.g., such as in a picture parameter set). A tile row refers to a rectangular area of ​​a CTU with a height specified by a syntax element (e.g., such as in a picture parameter set) and a width equal to the width of the picture.

[0067] In some examples, a tile may be partitioned into multiple bricks, each of which may include one or more CTU rows within the tile. A tile that is not partitioned into multiple bricks may also be referred to as a brick. However, a brick that is a true subset of a tile may not be referred to as a tile.

[0068] Tiles in a picture can also be arranged in slices. A slice can be an integer number of tiles of a picture that can be uniquely contained in a single Network Abstraction Layer (NAL) unit. In some examples, a slice includes multiple complete tiles or a continuous sequence of complete tiles of only one tile.

[0069] This disclosure may use "NxN" and "N by N" interchangeably to refer to the sample size of a block (such as a CU or other video block) in terms of vertical and horizontal dimensions, for example, 16x16 samples or 16 by 16 samples. Typically, a 16x16 CU will have 16 samples in the vertical direction (y=16) and 16 samples in the horizontal direction (x=16). Likewise, an NxNCU typically 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 may be arranged in rows and columns. Furthermore, a CU does not necessarily need to have the same number of samples in the horizontal direction as in the vertical direction. For example, a CU may include NxM samples, where M is not necessarily equal to N.

[0070] The video encoder 200 encodes video data representing prediction and / or residual information and other information for a CU. The prediction information indicates how the CU will be predicted in order to form a prediction block for the CU. The residual information typically represents the sample-by-sample difference between the samples of the CU before encoding and the prediction block.

[0071] To predict a CU, the video encoder 200 may typically form a prediction block for the CU through inter-frame prediction or intra-frame prediction. Inter-frame prediction typically refers to predicting a CU based on data of a previously decoded picture, while intra-frame prediction typically refers to predicting a CU based on previously decoded data of the same picture. To perform inter-frame prediction, the video encoder 200 may use one or more motion vectors to generate a prediction block. The video encoder 200 may typically perform a motion search to identify a reference block that closely matches the CU, for example, in terms of the difference between the CU and the reference block. The video encoder 200 may calculate a difference metric using the sum of absolute differences (SAD), the sum of squared differences (SSD), the mean absolute difference (MAD), the mean squared difference (MSD), or other such difference calculations to determine whether the reference block closely matches the current CU. In some examples, the video encoder 200 may use unidirectional prediction or bidirectional prediction to predict the current CU.

[0072] Some examples of VVC also provide an affine motion compensation mode, which can be considered an inter-frame prediction mode. In affine motion compensation mode, the video encoder 200 can determine two or more motion vectors representing non-translational motion (such as zooming in or out, rotation, perspective motion, or other irregular motion types).

[0073] To perform intra prediction, the video encoder 200 can select an intra prediction mode to generate a prediction block. Some examples of VVC provide sixty-seven intra prediction modes, including various directional modes, as well as planar mode and DC mode. Typically, the video encoder 200 selects an intra prediction mode that describes the neighboring samples of the current block (e.g., the block of the CU) based on which the samples of the current block are to be predicted. Assuming that the video encoder 200 decodes the CTU and CU in raster scan order (from left to right, from top to bottom), such samples may typically be above, above left, or to the left of the current block in the same picture as the current block.

[0074] The video encoder 200 encodes data indicating a prediction mode for the current block. For example, for inter-frame prediction mode, the video encoder 200 may encode data indicating which of various available inter-frame prediction modes to use, as well as motion information for the corresponding mode. For unidirectional or bidirectional inter-frame prediction, for example, the video encoder 200 may encode motion vectors using Advanced Motion Vector Prediction (AMVP) or Merge Mode. The video encoder 200 may use a similar mode to encode motion vectors for affine motion compensation mode.

[0075] After a prediction, such as intra-frame prediction or inter-frame prediction, for a block, the video encoder 200 may calculate residual data for the block. The residual data, such as a residual block, represents the sample-by-sample difference between the block and a prediction block for the block, which is formed using a corresponding prediction mode. The video encoder 200 may apply one or more transforms to the residual block to produce transformed data in a transform domain rather than a sample domain. For example, the video encoder 200 may apply a discrete cosine transform (DCT), an integer transform, a wavelet transform, or a conceptually similar transform to the residual video data. In addition, the video encoder 200 may apply a secondary transform, such as a mode-dependent non-separable secondary transform (MDNSST), a signal-dependent transform, a Karhunen-Loeve transform (KLT), etc., after the first transform. The video encoder 200 generates transform coefficients after applying the one or more transforms.

[0076] As described above, after any transform to produce transform coefficients, the video encoder 200 may perform quantization on the transform coefficients. Quantization generally refers to a process in which transform coefficients are quantized to potentially reduce the amount of data used to represent the transform coefficients, thereby providing further compression. By performing the quantization process, the video encoder 200 may reduce the bit depth associated with some or all transform coefficients. For example, the video encoder 200 may round down an n-bit value to an m-bit value during quantization, where n is greater than m. In some examples, to perform quantization, the video encoder 200 may perform a bitwise right shift of the value to be quantized.

[0077] After quantization, the video encoder 200 may scan the transform coefficients to produce a one-dimensional vector from a two-dimensional matrix including the quantized transform coefficients. The scan may be designed to place transform coefficients with higher energy (and therefore lower frequency) at the front of the vector and transform coefficients with lower energy (and therefore higher frequency) at the back of the vector. In some examples, the video encoder 200 may scan the quantized transform coefficients using a predefined scan order to produce a serialized vector and then entropy encode the quantized transform coefficients of the vector. In other examples, the video encoder 200 may perform adaptive scanning. After scanning the quantized transform coefficients to form a one-dimensional vector, the video encoder 200 may entropy encode the one-dimensional vector, for example, according to context-adaptive binary arithmetic coding (CABAC). The video encoder 200 may also entropy encode the values ​​of syntax elements used to describe metadata associated with the encoded video data for use by the video decoder 300 when decoding the video data.

[0078] To perform CABAC, the video encoder 200 may assign context within a context model to a symbol to be transmitted. The context may relate to, for example, whether the neighboring values ​​of the symbol are zero values. The probability determination may be based on the context assigned to the symbol.

[0079] The video encoder 200 may 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 the video decoder 300, for example, in a picture header, a block header, or a slice header. Similarly, the video decoder 300 may decode such syntax data to determine how to decode the corresponding video data.

[0080] In this way, the video encoder 200 can generate a bitstream that includes coded video data, such as syntax elements describing the partitioning of a picture into blocks (e.g., CUs) and prediction and / or residual information for the blocks. Ultimately, the video decoder 300 can receive the bitstream and decode the coded video data.

[0081] In general, the video decoder 300 performs a process that is inverse to the process performed by the video encoder 200 to decode the encoded video data of the bitstream. For example, the video decoder 300 may use CABAC to decode the values ​​of syntax elements for the bitstream in a manner substantially similar to, but inverse to, the CABAC encoding process of the video encoder 200. The syntax elements may define partitioning information for partitioning a picture into CTUs and partitioning each CTU according to a corresponding partitioning structure (such as a QTBT structure) to define CUs of the CTU. The syntax elements may also define prediction and residual information for a block (e.g., a CU) of video data.

[0082] The residual information may be represented by, for example, quantized transform coefficients. The video decoder 300 may inverse quantize and inverse transform the quantized transform coefficients of the block to reproduce a residual block for the block. The video decoder 300 uses the signaled prediction mode (intra-frame prediction or inter-frame prediction) and related prediction information (e.g., motion information for inter-frame prediction) to form a prediction block for the block. The video decoder 300 may then combine the prediction block and the residual block (on a sample-by-sample basis) to reproduce the original block. The video decoder 300 may perform additional processing, such as a deblocking process to reduce visual artifacts along block boundaries.

[0083] According to the technology of the present disclosure, the video encoder 200 and the video decoder 300 can be configured to determine and / or utilize SCIPU based on one or more example techniques described in the present disclosure. In some examples, the video encoder 200 and the video decoder 300 can utilize chroma block size to determine SCIPU. In some examples, the video encoder 200 and the video decoder 300 can utilize chroma block size and luma block size to determine SCIPU. The present disclosure also describes example techniques for removing narrow vertical intra blocks (e.g., 2xN sized blocks) and example techniques for adaptively splitting chroma regions of SCIPUs within a frame.

[0084] As described in more detail below, according to one or more examples described in this disclosure, determining and utilizing the SCIPU may result in better operation of the video encoder 200 and the video decoder 300. For example, block size may affect how quickly the video encoder 200 and the video decoder 300 can encode or decode a picture. Since there are more blocks in a picture, smaller blocks may result in longer encoding and decoding times than larger blocks, but may also result in reduced distortion. By using the techniques described in this disclosure, the operation of the video encoder 200 and the video decoder 300 can be improved to ensure that encoding and decoding are performed in a timely manner to minimize processing delays while still allowing improved video quality to be achieved through smaller blocks. Therefore, by selectively enabling and disabling the SCIPU based on the video decoding format, the example techniques described in this disclosure provide a practical application of techniques for video decoding that improves the overall operation of the video encoder 200 and the video decoder 300.

[0085] In general, the present disclosure may involve "signaling" certain information (such as syntax elements). The term "signaling" may generally refer to the transmission of values ​​for syntax elements and / or other data used to decode encoded video data. That is, video encoder 200 may signal values ​​for syntax elements in a bitstream. Generally, signaling refers to generating values ​​in a bitstream. As described above, source device 102 may transmit the bitstream to destination device 116 in substantially real time or in non-real time (such as may occur when storing syntax elements to storage device 112 for later retrieval by destination device 116).

[0086] Figure 2A and 2Bis a conceptual diagram illustrating an example quadtree binary tree (QTBT) structure 130 and a corresponding CTU 132. Solid lines represent quadtree splits, while 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, in this example, 0 indicates a horizontal split and 1 indicates a vertical split. For quadtree splits, since the quadtree node splits the block horizontally and vertically into 4 sub-blocks of equal size, there is no need to indicate the split type. Thus, the video encoder 200 can encode, and the video decoder 300 can decode, the following: syntax elements (such as split information) for the region tree level (i.e., solid lines) of the QTBT structure 130, and syntax elements (such as split information) for the prediction tree level (i.e., dashed lines) of the QTBT structure 130. The video encoder 200 may encode video data (such as prediction and transform data) for the CU represented by the terminal leaf node of the QTBT structure 130 , and the video decoder 300 may decode the video data.

[0087] generally, Figure 2B The CTU 132 may be associated with parameters defining the size of blocks corresponding to nodes at the first and second levels of the QTBT structure 130. These parameters may include a CTU size (indicating the size of the CTU 132 in samples), a minimum quadtree size (MinQTSize, indicating the minimum allowed quadtree leaf node size), a maximum binary tree size (MaxBTSize, indicating the maximum allowed binary tree root node size), a maximum binary tree depth (MaxBTDepth, indicating the maximum allowed binary tree depth), and a minimum binary tree size (MinBTSize, indicating the minimum allowed binary tree leaf node size).

[0088] The root node of the QTBT structure corresponding to the CTU can have four child nodes at the first level of the QTBT structure, each of which can be split according to quadtree partitioning. That is, the nodes at the first level are leaf nodes (no child nodes) or have four child nodes. The example of the QTBT structure 130 represents such nodes as including parent nodes and child nodes with solid branches. If the nodes at the first level are not larger than the maximum allowed binary tree root node size (MaxBTSize), these nodes can be further split by the corresponding binary tree. The binary tree splitting of a node can be iterated until the node resulting from the split reaches the minimum allowed binary tree leaf node size (MinBTSize) or the maximum allowed binary tree depth (MaxBTDepth). The example of the QTBT structure 130 represents such nodes as having dotted branches. The binary tree leaf nodes are called decoding units (CUs), which are used for prediction (e.g., intra-picture or inter-picture prediction) and transformation without any further partitioning. As discussed above, CUs can also be referred to as "video blocks" or "blocks."

[0089] In one example of a QTBT partitioning structure, the CTU size is set to 128x128 (luminance sample 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. Quadtree leaf nodes can have sizes from 16x16 (i.e., MinQTSize) to 128x128 (i.e., CTU size). If the leaf quadtree node is 128x128, then since the size exceeds MaxBTSize (i.e., 64x64 in this example), the leaf quadtree node will not be further split by the binary tree. Otherwise, the leaf quadtree node will be further split by the binary tree. Therefore, the quadtree leaf node is also the root node for the binary tree 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), it 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 the binary tree node. As described above, the leaf nodes of the binary tree are called CUs and are further processed according to prediction and transformation without further segmentation.

[0090] The following describes the partitioning structure implemented in VVC Draft 6 and HEVC. In HEVC, a video coder can split a CTU into CUs using a quadtree structure (denoted as a coding tree) to adapt to various local characteristics, as described in J. Chen, Y. Ye, S.H. Kim, “Algorithm description for Versatile Video Coding and Test Model 5 (VTM 5)”, JVET-N1002. The video encoder 200 determines whether to use inter-picture (temporal) prediction or intra-picture (spatial) prediction at the leaf-CU level to code a picture region. Depending on the PU split type, each leaf-CU can be further split into one, two, or four PUs. Within a PU, the same prediction process is applied, and relevant information is signaled in the coded video data on a PU basis. After obtaining the residual, the leaf-CU can be partitioned into TUs according to another quadtree structure (similar to the coding tree for CUs) based on a comparison of the predicted block with the original block of video data. The HEVC partitioning structure uses multiple partition types, namely CU, PU, ​​and TU.

[0091] In VVC, the concept of multiple partition unit types has been replaced by a quadtree structure, which includes nested multi-type trees with binary and ternary split structures. Therefore, VVC removes the separation of CU, PU, ​​and TU, unless the separation is required for CUs that are too large for the maximum transform length. VVC also supports greater flexibility in the shape of CU partitions. In the decoding tree structure, the CU can have a square or rectangular shape. The CTU is first partitioned by a quadtree (also known as a quadtree) structure. The quadtree leaf nodes are then further partitioned by a multi-type tree structure.

[0092] Figures 3A-3E is a conceptual diagram showing an example of a multi-type tree splitting pattern. Figures 3A-3E As shown in the figure, there are five types of splits in the multi-type tree structure. These five types of splits are Figure 3A The quadtree partitioning shown in Figure 3B The vertical binary tree split shown in (e.g., vertical binary split (SPLIT_BT_VER), Figure 3C Horizontal binary tree splits (e.g., horizontal binary splits (SPLIT_BT_HOR), Figure 3D The vertical ternary tree split shown in (e.g., vertical ternary split (SPLIT_TT_VER)) and in Figure 3EThe horizontal ternary tree splitting (e.g., SPLIT_TT_HOR as shown) is used. The multi-type leaf nodes correspond to CUs, and unless the CU is too large for the maximum transform length, the same splitting used for prediction processing is also used for transform processing without any further splitting. This means that in most cases, the CUs, PUs, and TUs have the same block size in a quadtree with a nested multi-type tree CB structure. An exception occurs when the maximum supported transform length is less than the width or height of the color component of the CU.

[0093] A CTU includes a luminance CTB and two chrominance CTBs. At the CU level, a CU is associated with a luminance CB and two chrominance CBs. In VVC, the chrominance and luminance CBs of an intra-coded CU can share a single tree structure or use different tree structures (referred to as a dual tree). For an inter slice, the chrominance and luminance CBs of a CU can share a tree structure. In an inter slice, there may be intra blocks. Using a local dual tree structure in an inter slice can avoid small chrominance intra blocks. In a local dual tree, all luminance blocks are intra-coded, intra-block copy coded, or palette coded, and the chrominance is not split. For the luminance component, the size of a CTU can be up to 128x128, and the size of the decoding unit can range from 4x4 to the entire size of the CTU. In this scenario, the size of the chrominance blocks can be 2x2, 2x4, or 4x2 in the 4:2:0 color format. That is, due to chrominance subsampling for non-4:4:4 video coding formats, a 4x4 luminance block can correspond to a chrominance block smaller than 4x4.

[0094] As described above, the example techniques described in this disclosure can be related to coding a block using an intra prediction mode. Intra prediction angles and wide-angle intra prediction are described below. Intra prediction involves a DC prediction mode, a planar prediction mode, and a direction (or angle) prediction mode. The direction prediction for a square block uses the directions between -135 degrees and 45 degrees of the current block in the Versatile Video Coding Test Model 2 (VTM2) (J. Chen, Y. Ye, S. Kim, "Algorithm description for Versatile Video Coding and Test Model 2 (VTM2)", the 11th JVET meeting, Ljubljana, Slovenia, July 2018, JVET-K1002), as Figure 4 shown.

[0095] In VTM2, the block structure for specifying the prediction block used for intra prediction is not limited to a square (width w = height h). Rectangular or non-square prediction blocks (w > h or w < h) can improve coding efficiency based on the characteristics of the content.

[0096] In such rectangular blocks, limiting the direction of intra prediction to -135 to 45 degrees may result in the use of farther reference samples instead of closer reference samples for intra prediction. This design is likely to have an impact on decoding efficiency. It may be more beneficial to relax the restriction so that closer reference samples (beyond -135 to 45 degrees) can be used for prediction. Figure 5 An example of this is given in . For example, Figure 5 An example of an 8x4 rectangular block identified as current block 500 is shown, where since the intra prediction direction is restricted to the range of -135 degrees to 45 degrees, closer reference samples (e.g., reference sample 502) are not used, but farther reference samples (e.g., reference sample 504) can be used.

[0097] During the 12th JVET meeting, modifications to wide-angle intra prediction were adopted in VVC Test Model 3.0 (VTM3), as described in the following documents: L. Zhao, X. Zhao, S. Liu, X. Li, “CE3-related: Unification of angular intra prediction for square and non-square blocks,” 12th JVET Meeting, Macao SAR, China, October 2018, JVET-L0279; J. Chen, Y. Ye, S. Kim, “Algorithm description for Versatile Video Coding and Test Model 3 (VTM3),” 12th JVET Meeting, Macao SAR, China, October 2018, JVET-L1002; and B. Bross, J. Chen, S. Liu, “Versatile Video Coding (Draft3),” 12th JVET Meeting, Macao SAR, China, October 2018, JVET-L1001.

[0098] This adoption of wide-angle intra prediction involves two modifications to unify angular intra prediction for square and non-square blocks. First, the angular prediction directions are modified to cover the diagonal directions for all block shapes. Second, for all block aspect ratios (square and non-square), all angular directions are kept within the range between the bottom-left diagonal direction and the top-right diagonal direction, e.g. Figures 6A-6C shown. Figure 6A It is shown that a square block (eg, coding unit 602) does not require angular mode remapping (eg, angular directions between diagonal direction 604 and diagonal direction 606 are available). Figure 6BAngular mode remapping is shown for horizontal non-square blocks, such as coding unit 612. For example, there is a mapping of modes A and B outside of diagonal direction 614 to modes inside diagonal direction 614 and diagonal direction 616. Figure 6C Angular remapping is shown for vertical non-square blocks, such as coding unit 622. For example, there is a mapping of modes A and B that lie outside of diagonal direction 624 to modes that lie within diagonal direction 624 and diagonal direction 626.

[0099] Additionally, the number of reference samples in the top reference row and left reference column is restricted to 2*width+1 and 2*height+1 for all block shapes. Figure 8 A diagram of the wider angle employed in VTM3 is provided in FIG. Figure 7 Although VTM3 defines 95 modes, only 67 of them may be allowed for any block size. The exact modes allowed depend on the ratio of the block width to the block height. The precise mode allowed is achieved by limiting the range of modes for a particular block size.

[0100] Figure 9 Specifies the mapping table between predModeIntra and intra prediction angle parameter intraPredAngle in VTM3, as described in JVET-L1001. Angular modes corresponding to non-square block diagonal, vertical and horizontal modes, and square block diagonal modes are used. Figure 9 In the , angle patterns with positive intraPredAngle values ​​are referred to as positive angle patterns (pattern index <18 or >50), while angle patterns with negative intraPredAngle values ​​are referred to as negative angle patterns (pattern index >18 and <50).

[0101] VVC Draft 6 supports 8 intra prediction modes for chroma components, including PLANAR, VER, HOR, DC, LM, MDLM_L, MDLM_T, and DM. In order to encode a chroma intra-coded CU, a flag is used to indicate whether the CU is DM-coded. If the CU is determined to be DM, the intra prediction mode of the corresponding luma component is used to obtain the prediction for the CU. Otherwise, the video encoder 200 notifies the video decoder 300 of the mode of the CU with a signal. The VER and HOR modes use the available reconstructed samples of the top and left neighboring blocks, respectively, to predict the current block. The PLANAR and DC modes use the available reconstructed samples of both the top and left neighboring blocks for prediction. For LM, MDLM_L, and MDLM_T, the reconstructed samples of the corresponding luma block are used for prediction.

[0102] The intra prediction samples are described below. Samples in the neighborhood of the CB are used for intra prediction of the block. Typically, the reconstructed reference sample lines closest to the left and top boundaries of the CB are used as reference samples for intra prediction. However, the following document also enables other samples in the neighborhood of the CB to be used as reference samples: VVC Working Draft 4, Bross et al., “Versatile Video Coding (Draft 4)”, Joint Video Experts Group (JVET) of ITU-T SG 16WP 3 and ISO / IEC JTC 1 / SC 29 / WG 11, 13th Meeting: Marrakech, Morocco, January 9-18, 2019, JVET-O1001-v7 (hereinafter referred to as “VVC Draft 4”).

[0103] In VVC draft 4, only reference lines with MRLIdx equal to 0, 1 and 3 can be used for luma components. For chroma components, only reference lines with MRLIdx equal to 0 can be used, such as Figure 10 The index of the reference row used to code the block is coded using a truncated unary codeword (values ​​0, 1, and 2 indicate rows with MRLIdx 0, 1, and 3, respectively). Planar and DC modes are not used for reference rows with MRLIdx>0. In some examples, only available samples of the neighborhood of the CB may be added to the reference array for intra prediction.

[0104] The SCIPU is described below. In typical hardware video encoders and decoders, processing throughput decreases when a picture has more small blocks. This decrease in processing throughput mainly comes from small intra blocks, because small inter blocks can be processed in parallel, while intra blocks have data dependencies between adjacent blocks (for example, predictor generation for an intra block requires reconstructed samples from the top and left boundaries of adjacent blocks) and are processed sequentially.

[0105] In HEVC, the worst-case processing throughput occurs when processing 4x4 chroma intra blocks. In VTM4.0, the minimum chroma intra block size is 2x2, and due to the use of new tools, the reconstruction process of chroma intra blocks has become very complicated.

[0106] To improve the worst-case processing throughput in VVC, SCIPU was proposed in the following document: Z.-Y. Lin, T.-D. Chuang, C.-Y. Chen, Y.-W. Huang, S.-M. Lei, Y. Zhao, H. Yang, "CE3-2.1.1 and CE3-2.1.2: Removing 2x2, 2x4, and 4x2 chroma CBs", JVET-O0050. SCIPU was adopted into VVC Draft 6 at the 15th JVET in Gothenburg. The goal of the technique used for SCIPU is to disable chroma intra CBs with less than 16 chroma samples by constraining the splitting of chroma intra CBs.

[0107] In a single coding tree, a SCIPU is defined as a coding tree node whose chroma block size is greater than or equal to a threshold (TH) chroma samples and has at least one sub-luminance block of less than 4TH luminance samples, where TH is set to 16, as an example. In some examples, in each SCIPU, all CBs are inter-frame or all CBs are non-inter-frame (i.e., intra-frame or IBC). In the case of a non-inter-frame SCIPU, in some examples, the chroma of the non-inter-frame SCIPU may not (e.g., should not) be further split, and the luminance of the SCIPU is allowed to be further split. In this way, the minimum chroma intra-frame CB size is 16 chroma samples, and 2x2, 2x4, and 4x2 chroma CBs are removed. In addition, in the case of a non-inter-frame SCIPU, chroma scaling is not applied.

[0108] exist Figure 11A and 11B Two SCIPU examples are shown in . Figure 11A In , one chroma CB with 8x4 chroma samples and three luma CBs (4x8, 8x8, 4x8 luma CB) form one SCIPU, because the ternary tree (TT) split from 8x4 chroma samples will result in a chroma CB that is less than 16 chroma samples. Figure 11B , one chroma CB with 4x4 chroma samples (on the left side of 8x4 chroma samples) and three luma CBs (8x4, 4x4, 4x4 luma CB) form one SCIPU, and another chroma CB with 4x4 samples (on the right side of 8x4 chroma samples) and two luma CBs (8x4, 8x4 luma CB) form one SCIPU, because the binary tree (BT) split from the 4x4 chroma samples will result in a chroma CB that is less than 16 chroma samples. Figure 12A –12S is a conceptual diagram showing an additional example of SCIPU. The size is in units of luma components.

[0109] If the current slice is an I slice, or after one further split, the current SCIPU has a 4x4 luma partition in it, the type of SCIPU is inferred to be non-inter (because inter 4x4 is not allowed in VVC); otherwise, the type of SCIPU (inter or non-inter) is indicated by a signaled flag before parsing the CU in the SCIPU. By applying the above two methods, the worst-case hardware processing throughput occurs when processing 4x4, 2x8, or 8x2 chroma blocks instead of 2x2 chroma blocks. The worst-case hardware processing throughput is the same as in HEVC and 4 times that of VTM5.0.

[0110] However, as described in VVC draft 6, there may be problems in determining and utilizing SCIPUs. As an example of problems with determining and utilizing SCIPUs, in VVC draft 6, SCIPUs are decided (e.g., determined) based on the size and split of the luma region (e.g., samples in the luma component). Using this approach, SCIPUs cannot work correctly with different chroma formats. As an example, Figure 13 A luma block is shown with a size of 16x8 and a ternary tree (TT) split in the vertical direction and a threshold of 16 samples in the chroma size. Figure 13 The block size of the corresponding chroma area of ​​the luminance block uses different chroma formats, such as Figures 14A-14C shown.

[0111] In the 4:2:0 format, the chroma area has a size of 4x8, such as Figure 14A Since TT vertical splitting produces 2x4 blocks, they (eg, chroma blocks including chroma regions, such as 4x8 chroma blocks) are considered as SCIPUs (8 samples < 16).

[0112] In the 4:2:2 format, the chroma area has a size of 8x8, such as Figure 14B As shown in FIG. 1 . For TT vertical splitting, the minimum size of a sub-block is 2×8. Therefore, it (e.g., a chroma block with a size of 8×8 or a sub-block with a size of 2×8) may not be considered as a SCIPU.

[0113] In the 4:4:4 format, the chroma area has a size of 8x16, such as Figure 14C As shown. For TT vertical split, the minimum sub-block size is 4x8. In this case, chroma is not SCIPU.

[0114] As another example of issues with determining and utilizing SCIPUs, the implementation of SCIPUs in VVC draft 6 does not allow intra prediction for 2x2 and 2x4 blocks. However, VVC draft 6 does allow vertical narrow intra chroma blocks. This type of block size (e.g., vertical narrow intra chroma blocks) may degrade data access performance.

[0115] As another example of the problem of determining and utilizing SCIPUs, in VVC draft 6, the splitting of the chroma region of the SCIPU within a frame is not allowed to avoid 2x2, 2x4, and 4x2. However, for large chroma regions of SCIPU (e.g., 8x4 and 4x8), some splits may not produce such small blocks. Disabling the splitting of these large chroma regions may result in performance losses.

[0116] This disclosure describes example techniques for solving one or more of the above-mentioned example problems. This disclosure also describes techniques for signaling whether to use inter-frame prediction or intra-frame prediction for decoding a SCIPU. The example techniques can be performed individually or together in any or multiple different combinations. Although the example techniques can solve the above-mentioned problems, the example techniques should not be considered limited to solving one or more of the above-mentioned problems.

[0117] In addition, for ease of understanding only, some example techniques are described with respect to modifications to VVC Draft 6, particularly Section 7.4.9.4 of VVC Draft 6. A portion of Section 7.4.9.4 of VVC Draft 6 is reproduced below to facilitate understanding of potential modifications to VVC Draft 6 according to one or more examples described in this disclosure.

[0118] 7.4.9.4 Decoding Tree Semantics

[0119] …

[0120] For each CTU, the variable modeTypeCondition is derived as follows:

[0121] – If one of the following conditions is true, then set modeTypeCondition equal to 0

[0122] –slice_type == 1 and qtbtt_dual_tree_intra_flag is equal to 1

[0123] –modeTypeCurr is not equal to MODE_TYPE_ALL

[0124] – Otherwise, if one of the following conditions is true, then set modeTypeCondition equal to 1

[0125] –cbWidth*cbHeight is equal to 64 and split_qt_flag is equal to 1

[0126] –cbWidth*cbHeight is equal to 64 and MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or SPLIT_TT_VER

[0127] –cbWidth*cbHeight is equal to 32 and MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or SPLIT_BT_VER

[0128] – Otherwise, if one of the following conditions is true, then set modeTypeCondition equal to 1 + (slice_type != I?1:0)

[0129] –cbWidth*cbHeight is equal to 64 and MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or SPLIT_BT_VER

[0130] –cbWidth*cbHeight is equal to 128 and MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or SPLIT_TT_VER

[0131] – Otherwise, set modeTypeCondition equal to 0

[0132] The following describes an example of using chroma block size to determine SCIPUs. For example, SCIPUs can be determined (e.g., determined) based on the chroma size and the splitting of the luma region. In some examples, for the splitting of the luma region, the size of the chroma region can be derived by scaling the luma size by a factor that depends on the chroma format. If the splitting of the luma partition is applied to the chroma region to produce a chroma sub-block with a size less than a threshold TH, the luma region and the corresponding chroma region are considered SCIPUs (e.g., the luma region, the corresponding chroma region, or both the luma region and the corresponding luma region).

[0133] In one example, the derivation of the variable modeTypeCondition in VVC draft 6 may be modified as follows:

[0134] 7.4.9.4 Decoding Tree Semantics

[0135] …

[0136] The variable modeTypeCondition is derived as follows:

[0137] – If one of the following conditions is true, then set modeTypeCondition equal to 0

[0138] –slice_type == 1 and qtbtt_dual_tree_intra_flag is equal to 1

[0139] –modeTypeCurr is not equal to MODE_TYPE_ALL

[0140] – Otherwise, if one of the following conditions is true, then set modeTypeCondition equal to 1

[0141] –(cbWidth / SubWidthC)*(cbHeight / SubHeightC) is equal to 32 and split_qt_flag is equal to 1

[0142] –(cbWidth / SubWidthC)*(cbHeight / SubHeightC) is equal to 16 and split_qt_flag is equal to 1

[0143] –(cbWidth / SubWidthC)*(cbHeight / SubHeightC) is equal to 16 and MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or SPLIT_TT_VER

[0144] –(cbWidth / SubWidthC)*(cbHeight / SubHeightC) is equal to 32 and MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or SPLIT_TT_VER and (SubHeightC == 2 or SubWidthC == 2)

[0145] –(cbWidth / SubWidthC)*(cbHeight / SubHeightC) is equal to 8 and MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or SPLIT_BT_VER

[0146] – Otherwise, if one of the following conditions is true, then set modeTypeCondition equal to 1 + (slice_type != I?1:0)

[0147] –(cbWidth / SubWidthC)*(cbHeight / SubHeightC) is equal to 16 and MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or SPLIT_BT_VER

[0148] –(cbWidth / SubWidthC)*(cbHeight / SubHeightC) is equal to 32 and MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or SPLIT_TT_VER

[0149] – Otherwise, set modeTypeCondition equal to 0

[0150] …

[0151] In some examples, SCIPU can be disabled for YUV 4:4:4 format (chroma_format_idc equal to 3), where the chroma components have the same size as the luma components. The corresponding derivation of modeTypeCondition is modified to:

[0152] 7.4.9.4 Decoding Tree Semantics

[0153] …

[0154] The variable modeTypeCondition is derived as follows:

[0155] – If one of the following conditions is true, then set modeTypeCondition equal to 0

[0156] –slice_type == 1 and qtbtt_dual_tree_intra_flag is equal to 1

[0157] –modeTypeCurr is not equal to MODE_TYPE_ALL

[0158] –chroma_format_idc==3

[0159] …

[0160] In some examples, the SCIPU may be disabled for monochrome sampling (chroma_format_idc equal to 0) where there is only one sample array (nominaly considered as a luma array). The corresponding derivation of modeTypeCondition is modified to:

[0161] 7.4.9.4 Decoding Tree Semantics

[0162] …

[0163] The variable modeTypeCondition is derived as follows:

[0164] – If one of the following conditions is true, then set modeTypeCondition equal to 0

[0165] –slice_type == 1 and qtbtt_dual_tree_intra_flag is equal to 1

[0166] –modeTypeCurr is not equal to MODE_TYPE_ALL

[0167] –chroma_format_idc==0

[0168] …

[0169] In another example, SCIPU can be disabled for YUV 4:4:4 format and monochrome sampling, while SCIPU can be enabled for other YUV formats (e.g., a combination of one or more of the above example techniques). When SCIPU is enabled, the chroma size and the split of the corresponding luma partition can be used to determine whether the region is a SCIPU. In this case, the corresponding derivation of modeTypeCondition in VVC draft 6 can be modified as follows:

[0170] 7.4.9.4 Decoding Tree Semantics

[0171] …

[0172] The variable modeTypeCondition is derived as follows:

[0173] – If one of the following conditions is true, then set modeTypeCondition equal to 0

[0174] –slice_type == 1 and qtbtt_dual_tree_intra_flag is equal to 1

[0175] –modeTypeCurr is not equal to MODE_TYPE_ALL

[0176] –chroma_format_idc==0

[0177] –chroma_format_idc==33

[0178] – Otherwise, if one of the following conditions is true, then set modeTypeCondition equal to 1

[0179] –(cbWidth / SubWidthC)*(cbHeight / SubHeightC) is equal to 32 and split_qt_flag is equal to 1

[0180] –(cbWidth / SubWidthC)*(cbHeight / SubHeightC) is equal to 16 and split_qt_flag is equal to 1

[0181] –(cbWidth / SubWidthC)*(cbHeight / SubHeightC) is equal to 16 and MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or SPLIT_TT_VER

[0182] –(cbWidth / SubWidthC)*(cbHeight / SubHeightC) is equal to 8 and MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or SPLIT_BT_VER

[0183] – Otherwise, if one of the following conditions is true, then set modeTypeCondition equal to 1 + (slice_type != I?1:0)

[0184] –(cbWidth / SubWidthC)*(cbHeight / SubHeightC) is equal to 16 and MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or SPLIT_BT_VER

[0185] –(cbWidth / SubWidthC)*(cbHeight / SubHeightC) is equal to 32 and MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or SPLIT_TT_VER

[0186] – Otherwise, set modeTypeCondition equal to 0

[0187] In the above text, chroma_format_idc=0 refers to a monochrome chroma format; chroma_format_idc=1 refers to a 4:2:0 chroma format; chroma_format_idc=2 refers to a 4:2:2 chroma format; and chroma_format_idc=3 refers to a 4:4:4 chroma format.

[0188] In some examples, the video encoder 200 and the video decoder 300 can be configured to use the chroma block size and the luma block size to determine the SCIPU. The SCIPU can be an intra-coded area, an intra-SCIPU area, or a non-inter-frame area, where all blocks within the SCIPU are intra-coded. The SCIPU can additionally or alternatively be an inter-SCIPPU, where all blocks within the SCIPU are inter-coded. In VVC Draft 6, inter-blocks cannot be smaller than 4x4. Therefore, for the smallest block in the current SCIPU, the block cannot be an inter-block and is inferred to be an intra-block.

[0189] In some examples, the video encoder 200 and the video decoder 300 can be configured to use the splitting of the luminance area of ​​the partition, the size of the minimum luminance block, and the size of the minimum chrominance block to determine whether the block is a SCIPU and whether the block is an inter-frame SCIPU or a non-inter-frame SCIPU or whether the block is an inter-frame SCIPU or an intra-frame SCIPU, where in some examples, an intra-frame SCIPU is considered an example of a non-inter-frame SCIPU. In one example, if the size of the minimum luminance block and the size of the minimum chrominance block of the partition are less than a threshold (TH), then it (e.g., the minimum chrominance block or the minimum luminance block) is considered a SCIPU. Otherwise, it (e.g., the minimum chrominance block or the minimum luminance block) is not a SCIPU. Furthermore, in this example, if it (e.g., the minimum chroma block or the minimum luma block) is determined to be a SCIPU and the SCIPU is in an intra slice, or the size of the minimum luma block in the region is smaller than the minimum size enabled for an inter block, then the SCIPU is implicitly an intra SCIPU or the SCIPU is implicitly a non-inter SCIPU (in some examples, an intra SCIPU can be considered an example of a non-inter SCIPU). Otherwise, it (e.g., the minimum chroma block or the minimum luma block) can be an intra SCIPU or an inter SCIPU, or can be a non-inter SCIPU or an inter SCIPU.

[0190] The derivation of modeTypeCondition in VVC draft 6 can be modified as follows:

[0191] 7.4.9.4 Decoding Tree Semantics

[0192] …

[0193] The variable min_luma_blk_size is derived as follows:

[0194] – If qtbtt_dual_tree_intra_flag is equal to 1 or MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or SPLIT_TT_VER, then min_luma_blk_size = (cbWidth*cbHeight) / 4

[0195] Otherwise, if MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or SPLIT_BT_VER, then min_luma_blk_size = (cbWidth*cbHeight) / 2

[0196] Otherwise, min_luma_blk_size = (cbWidth*cbHeight)

[0197] – The variable min_chroma_blk_size is derived as follows:

[0198] min_chroma_blk_size=min_luma_blk_size / (SubWidthC*SubHeightC)

[0199] The variable modeTypeCondition is derived as follows:

[0200] – If one of the following conditions is true, then set modeTypeCondition equal to 0

[0201] –slice_type == 1 and qtbtt_dual_tree_intra_flag is equal to 1

[0202] –modeTypeCurr is not equal to MODE_TYPE_ALL

[0203] –chroma_format_idc==0

[0204] –chroma_format_idc==3

[0205] –min_chroma_blk_size>=16

[0206] – Otherwise, if min_luma_blk_size <= 16, set modeTypeCondition equal to 1

[0207] – Otherwise, set modeTypeCondition to 1+(slice_type != I?1:0).

[0208] In some examples, the video encoder 200 and the video decoder 300 can be configured to prevent or remove narrow vertical intra blocks (e.g., 2xN). In some examples, a 2xN split can be disabled in a separate tree (e.g., a dual tree structure or a local dual tree structure). In one example, if the block width is equal to 8, then ternary tree (TT) splitting can be disabled. In another example, if the block width is equal to 4, then vertical splitting can be disabled. In some examples, intra mode is disabled for 4xN luma blocks in a single tree.

[0209] In some examples using a single tree, the video encoder 200 and the video decoder 300 can be configured to apply SCIPU with extensions. For example, if the chroma width is 8 and the split of the luma component is a ternary tree (TT), then the region (e.g., the chroma width is 8) can be considered as a SCIPU. As another example, if the chroma width is 4 and the split of the luma region is vertical, then the region (e.g., the chroma width is 4) can be considered as a SCIPU.

[0210] In some examples, the video encoder 200 and the video decoder 300 can be configured to avoid combined intra-inter prediction mode (CIIP) for 4xN blocks. That is, CII can be disabled for 4xN blocks. In some examples, when CIIP mode is applied to a 4xN block, combined prediction (e.g., using a combination of intra and inter prediction) can be applied only to the luma component, while chroma components can be predicted using only one of intra or inter prediction (e.g., using only inter prediction). CIIP blocks can be present in inter slices and use a shared tree.

[0211] In some examples, the video encoder 200 and the video decoder 300 can be configured to adaptively split the chroma region of the intra SCIPU. As an example, the example technology can enable the splitting of the chroma region in the intra SCIPU. The example technology can enable the splitting of the chroma region in the non-inter SCIPU (in some examples, the intra SCIPU can be regarded as an example of a non-inter SCIPU). In some examples, the splitting that results in the minimum sub-block size that meets the block size limit can be allowed. For example, if the chroma region of the intra SCIPU is 8xN, vertical splitting can be allowed. In some examples, if N=4, horizontal splitting can be allowed. In some examples, if N=8, quadtree splitting, vertical splitting and horizontal splitting can be allowed. In some examples, if N>8, vertical splitting, horizontal splitting and TT horizontal splitting can be allowed.

[0212] In some examples, if the chroma region of the intra-frame SCIPU is 4x8, horizontal BT (binary tree) splitting may be allowed. In another example, if the chroma region of the intra-frame SCIPU is 4xN, horizontal BT splitting may be allowed. In another example, if the chroma region of the intra-frame SCIPU is 4xN (N>8), horizontal splitting including BT horizontal splitting and TT (ternary tree) horizontal splitting may be allowed.

[0213] In some examples, the splitting candidates for the chroma regions in an intra SCIPU may depend on the splitting of the corresponding luma blocks. As an example, if luma is not split, then chroma splitting is not allowed. As an example, the chroma splitting direction cannot be orthogonal to the luma splitting direction. In one example, if the splitting of the luma block is vertical, then horizontal splitting may not be allowed for the chroma intra SCIPU. In one example, if the splitting of the luma block is horizontal, then vertical splitting may not be allowed for the chroma intra SCIPU.

[0214] This disclosure also describes an example of SCIPU signaling. In one example of adaptation of SCIPUs in VVC draft 6, a flag is signaled to indicate whether the SCIPU is an inter-frame SCIPU or an intra-frame SCIPU. The signaling utilizes a new syntax, and the new syntax is different from the prediction mode. This disclosure describes an example of an alternative signaling scheme for SCIPUs.

[0215] In a first aspect, signaling of the SCIPU may not be required, and the type of the SCIPU may be derived from the signaling of the prediction mode of the first block in the SCIPU. In this example, no additional signaling syntax may be required. The SCIPU type may be derived as follows. As an example, if the first block of the SCIPU is inter, the SCIPU is implicitly considered to be inter and the prediction mode of all blocks in the SCIPU is inter. As another example, when IBC (Intra Block Copy) is disabled, if the mode of the first block is intra, the SCIPU is implicitly considered to be non-inter, and the modes of the remaining blocks are implicitly signaled (e.g., implicitly determined) to be intra. As another example, when IBC is enabled, if the mode of the first block is intra or IBC, the SCIPU is implicitly considered to be non-inter, and the modes of the remaining blocks are explicitly signaled to be intra or IBC.

[0216] In a second aspect, the type of SCIPU (intra-frame or inter-frame) can be explicitly signaled using the following examples. As an example, the signaling of the SCIPU flag can share the context of the context used to signal the prediction mode of the block. For example, the context used to encode or decode the SCIPU flag can be the same context used to encode or decode the information of the prediction mode of the block. In this example, the derivation of the context index is the same as the derivation of the context index in conventional prediction mode decoding. For example, the derivation technique used by the video encoder 200 and the video decoder 300 to derive the context index for the context used to encode or decode the SCIPU flag can be the same derivation technique used by the video encoder 200 and the video decoder 300 to derive the context index for the context used to encode and decode the information indicating the prediction mode of the block.

[0217] In some examples of the second aspect, the signaling of the SCIPU can be the same as the signaling of the pattern of the first block in the SCIPU. The SCIPU type of the SCIPU can be derived using the same techniques as described above with respect to the first aspect. However, there may be some differences from the first aspect. For example, in the first aspect, it may be necessary to check whether the block is the first block in the SCIPU. In some examples of the second aspect, it may not be necessary to check whether the block is the first block in the SCIPU.

[0218] In some examples of the second aspect, the SCIPU flag can be used to indicate whether the SCIPU is an inter-frame SCIPU, an intra-frame SCIPU, or an IBC SCIPU, wherein the prediction mode of all blocks in the SCIPU is the same as the type of the SCIPU. For example, although the SCIPU flag is described, in some examples, a syntax element with multiple bits can be used to indicate whether the SCIPU is an inter-frame SCIPU, an intra-frame SCIPU, or an IBC SCIPU. In some examples, for all of the inter-frame SCIPU, the intra-frame SCIPU, and the IBC SCIPU, the prediction mode of all blocks in the SCIPU can be the same as the type of the SCIPU. In some examples, for one or more (but not necessarily all) of the inter-frame SCIPU, the intra-frame SCIPU, and the IBC SCIPU, the prediction mode of all blocks in the SCIPU can be the same as the type of the SCIPU.

[0219] In some examples, the SCIPU flag can be removed (e.g., not signaled) and the prediction mode of all luma blocks in the SCIPU region can be signaled. In such examples, the SCIPU type of the SCIPU can be determined (e.g., by the video encoder 200 or the video decoder 300) based on the prediction mode of one or more (e.g., any) blocks in the blocks in the SCIPU region. In the video encoder 200, encoder constraints can be imposed so that inter blocks may not (e.g., cannot) be mixed with intra or IBC blocks in the SCIPU region. For example, in the SCIPU region, if a block is decoded using inter prediction, then in some examples, the other blocks in the SCIPU region may not be intra predicted or predicted in IBC mode.

[0220] Figure 15 is a block diagram illustrating an example video encoder 200 that may perform the techniques of this disclosure. Figure 15 This is provided for purposes of explanation and should not be considered limiting of the techniques generally exemplified and described in this disclosure. For purposes of explanation, this disclosure describes video encoder 200 in the context of video coding standards such as the HEVC video coding standard and the developing H.266 video coding standard. However, the techniques of this disclosure are not limited to these video coding standards and are generally applicable to video encoding and decoding.

[0221] exist Figure 15 In the example of FIG, the video encoder 200 includes a video data memory 230, a mode selection unit 202, a residual generation unit 204, a transform processing unit 206, a quantization unit 208, an inverse quantization unit 210, an inverse transform processing unit 212, a reconstruction unit 214, a filter unit 216, a decoded picture buffer (DPB) 218, and an entropy coding unit 220. Any one or all of the video data memory 230, the mode selection unit 202, the residual generation unit 204, the transform processing unit 206, the quantization unit 208, the inverse quantization unit 210, the inverse transform processing unit 212, the reconstruction unit 214, the filter unit 216, the DPB 218, and the entropy coding unit 220 may be implemented in one or more processors or in processing circuitry. Furthermore, the video encoder 200 may include additional or alternative processors or processing circuitry to perform these and other functions.

[0222] The video data memory 230 may store video data to be encoded by the components of the video encoder 200. The video encoder 200 may receive video data from, for example, the video source 104 ( Figure 1) receives video data stored in the video data memory 230. The DPB 218 can act as a reference picture memory that stores reference video data for use when the video encoder 200 predicts subsequent video data. The video data memory 230 and the DPB 218 can be formed by 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 the DPB 218 can be provided by the same memory device or a separate memory device. In various examples, the video data memory 230 can be on-chip with other components of the video encoder 200 (as shown), or off-chip relative to those components.

[0223] In this disclosure, references to video data memory 230 should not be construed as limited to memory internal to the video encoder 200 (unless specifically described as such), or to memory external to the video encoder 200 (unless specifically described as such). Rather, references to video data memory 230 should be understood as reference memory that stores video data received by the video encoder 200 for encoding (e.g., video data for a current block to be encoded). Figure 1 The memory 106 may also provide temporary storage for outputs from the various units of the video encoder 200 .

[0224] Explained Figure 15 The various units of the video encoder 200 are described to help understand 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 refer to circuits that provide specific functions and are pre-set with respect to the operations that can be performed. Programmable circuits refer to circuits that can be programmed to perform various tasks and provide flexible functionality with respect to 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 the 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 performed by fixed-function circuits are generally immutable. In some examples, one or more of these units can be different circuit blocks (fixed-function or programmable), and in some examples, one or more units can be integrated circuits.

[0225] The video encoder 200 may include an arithmetic logic unit (ALU), an elementary function unit (EFU), a digital circuit, an analog circuit, and / or a programmable core formed by a programmable circuit. In an example where the operation of the video encoder 200 is performed using software executed by a programmable circuit, the memory 106 ( Figure 1 ) may store object code for software that video encoder 200 receives and executes, or another memory (not shown) within video encoder 200 may store such instructions.

[0226] The video data memory 230 is configured to store the received video data. The video encoder 200 can retrieve the picture of the video data from the video data memory 230 and provide the video data to the residual generation unit 204 and the mode selection unit 202. The video data in the video data memory 230 can be the original video data to be encoded.

[0227] The mode selection unit 202 includes a motion estimation unit 222, a motion compensation unit 224, and an intra prediction unit 226. The mode selection unit 202 may include additional functional units that perform video prediction according to other prediction modes. For example, the mode selection unit 202 may include a palette unit, an intra block copy unit (which may be part of the motion estimation unit 222 and / or the motion compensation unit 224), an affine unit, a linear model (LM) unit, etc.

[0228] The mode selection unit 202 typically coordinates multiple encoding passes to test combinations of encoding parameters and the resulting rate-distortion values ​​for such combinations. The encoding parameters may include the partitioning of a CTU into CUs, the prediction mode used for a CU, the transform type used for the residual data of a CU, the quantization parameter used for the residual data of a CU, etc. The mode selection unit 202 may ultimately select a combination of encoding parameters that has a better rate-distortion value than other tested combinations.

[0229] The video encoder 200 may partition a picture retrieved from the video data memory 230 into a series of CTUs and encapsulate one or more CTUs into a slice. The mode selection unit 202 may partition the CTUs of the picture according to a tree structure (such as the QTBT structure or quadtree structure of HEVC described above). As described above, the video encoder 200 may partition the CTUs according to the tree structure to form one or more CUs. Such CUs may also be generally referred to as "video blocks" or "blocks."

[0230] Typically, mode select 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 the current block (e.g., the current CU, or, in HEVC, the overlapping portions of a PU and TU). To inter-predict the current block, motion estimation unit 222 may perform a motion search to identify one or more closely matching reference blocks in one or more reference pictures (e.g., one or more previously decoded pictures stored in DPB 218). Specifically, motion estimation unit 222 may calculate values ​​representing how similar potential reference blocks are to the current block, such as based on sum of absolute differences (SAD), sum of squared differences (SSD), mean absolute difference (MAD), mean squared difference (MSD), and the like. Motion estimation unit 222 may typically perform these calculations using the sample-by-sample difference between the current block and the reference block under consideration. Motion estimation unit 222 may identify the reference block with the lowest value resulting from these calculations, indicating the reference block that most closely matches the current block.

[0231] Motion estimation unit 222 may form one or more motion vectors (MVs) that define the position of a reference block in a reference picture relative to the position of a current block in the current picture. Motion estimation unit 222 may then provide the motion vectors to motion compensation unit 224. For example, for unidirectional inter prediction, motion estimation unit 222 may provide a single motion vector, while for bidirectional inter prediction, motion estimation unit 222 may provide two motion vectors. Motion compensation unit 224 may then use the motion vectors to generate a prediction block. For example, motion compensation unit 224 may use the motion vectors to retrieve data for the reference block. As another example, if the motion vectors have fractional sample precision, motion compensation unit 224 may interpolate values ​​for the prediction block based on one or more interpolation filters. Furthermore, for bidirectional inter prediction, motion compensation unit 224 may retrieve data for two reference blocks identified by the respective motion vectors and combine the retrieved data, for example, by sample-by-sample averaging or weighted averaging.

[0232] As another example, for intra prediction or intra prediction decoding, the intra prediction unit 226 can generate a prediction block based on samples adjacent to the current block. For example, for directional mode, the intra prediction unit 226 can generally mathematically combine the values ​​of adjacent samples and pad these calculated values ​​across the current block in a defined direction to produce a prediction block. As another example, for DC mode, the intra prediction unit 226 can calculate the average of the adjacent samples of the current block and generate a prediction block to include the obtained average for each sample of the prediction block. When encoding a block, the intra prediction unit 226 can enable and disable the SCIPU based on the chroma subsampling format of the video data as described in the present disclosure.

[0233] Mode selection unit 202 provides the prediction block to residual generation unit 204. Residual generation unit 204 receives the original, unencoded version of the current block from video data memory 230 and the prediction block from mode selection unit 202. Residual generation unit 204 calculates the sample-by-sample difference between the current block and the prediction block. The resulting sample-by-sample difference defines a residual block for the current block. In some examples, residual generation unit 204 may also determine the difference between sample values ​​in the residual block to generate the residual block using residual differential pulse coded modulation (RDPCM). In some examples, residual generation unit 204 may be formed using one or more subtractor circuits that perform binary subtraction.

[0234] In the example where the mode select unit 202 partitions the CU into PUs, each PU may be associated with a luma prediction unit and a corresponding chroma prediction unit. The video encoder 200 and the video decoder 300 may support PUs of various sizes. As noted above, the size of a CU may refer to the size of the luma CB of the CU, while the size of a PU may refer to the size of the luma prediction unit of the PU. Assuming a particular CU size of 2Nx2N, the video encoder 200 may support PU sizes of 2Nx2N or NxN for intra prediction, and symmetrical PU sizes of 2Nx2N, 2NxN, Nx2N, NxN, or similar sizes for inter prediction. The video encoder 200 and the video decoder 300 may also support asymmetric partitioning for PU sizes of 2NxnU, 2NxnD, nLx2N, and nRx2N for inter prediction.

[0235] In an example where the mode selection unit does not further split the CU into PUs, each CU can be associated with a luma CB and a corresponding chroma CB. As described above, the size of a CU can refer to the size of the luma CB of the CU. The video encoder 200 and the video decoder 300 can support CU sizes of 2Nx2N, 2NxN, or Nx2N.

[0236] 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), mode selection unit 202 generates a prediction block for the current block being encoded via the corresponding unit associated with the coding technique. In some examples (such as palette mode coding), mode selection unit 202 may not generate a prediction block, but instead generate syntax elements that indicate how to reconstruct the block based on the selected palette. In such a mode, mode selection unit 202 may provide these syntax elements to entropy coding unit 220 for encoding.

[0237] 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 calculates the sample-by-sample difference between the prediction block and the current block.

[0238] 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 may apply various transforms to the residual block to form the transform coefficient block. For example, the transform processing unit 206 may 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 may perform multiple transforms on the residual block, such as 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.

[0239] The quantization unit 208 may quantize the transform coefficients in the transform coefficient block to produce a quantized transform coefficient block. The quantization unit 208 may quantize the 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) may 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 may result in a loss of information, and therefore, the quantized transform coefficients may have a lower precision than the original transform coefficients produced by the transform processing unit 206.

[0240] The inverse quantization unit 210 and the inverse transform processing unit 212 may apply inverse quantization and inverse transform, respectively, to the quantized transform coefficient block to reconstruct a residual block from the transform coefficient block. The reconstruction unit 214 may 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 may add samples of the reconstructed residual block to corresponding samples from the prediction block generated by the mode selection unit 202 to generate a reconstructed block.

[0241] Filter unit 216 may perform one or more filter operations on the reconstructed block. For example, filter unit 216 may perform a deblocking operation to reduce blocking artifacts along the edges of the CU. In some examples, the operations of filter unit 216 may be skipped.

[0242] The video encoder 200 stores the reconstructed block in the DPB 218. For example, in an example where the operation of the filter unit 216 is not performed, the reconstruction unit 214 can store the reconstructed block in the DPB 218. In an example where the operation of the filter unit 216 is performed, the filter unit 216 can store the filtered reconstructed block in the DPB 218. The motion estimation unit 222 and the motion compensation unit 224 can retrieve a reference picture formed by the reconstructed (and potentially filtered) block from the DPB 218 to perform inter-frame prediction on blocks of subsequently encoded pictures. In addition, the intra-frame prediction unit 226 can use the reconstructed block of the current picture in the DPB 218 to perform intra-frame prediction on other blocks in the current picture.

[0243] In general, entropy coding unit 220 may entropy encode syntax elements received from other functional components of video encoder 200. For example, entropy coding unit 220 may entropy encode quantized transform coefficient blocks from quantization unit 208. As another example, entropy coding unit 220 may entropy encode prediction syntax elements (e.g., motion information for inter-frame prediction or intra-frame mode information for intra-frame prediction) from mode selection unit 202. Entropy coding unit 220 may perform one or more entropy encoding operations on syntax elements, another example of video data, to generate entropy-encoded data. For example, entropy coding unit 220 may 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 coding unit 220 may operate in a bypass mode in which syntax elements are not entropy encoded.

[0244] The video encoder 200 may output a bitstream including entropy-encoded syntax elements required for reconstructing blocks of a slice or picture. Specifically, the entropy encoding unit 220 may output a bitstream.

[0245] The above operations are described with respect to blocks. Such descriptions should be understood as operations for luma CBs and / or chroma CBs. As described above, in some examples, the luma CB and chroma CB are the luma component and chroma component of a CU. In some examples, the luma CB and chroma CB are the luma component and chroma component of a PU.

[0246] In some examples, the operations performed for the luma CB do not need to be repeated for the chroma CB. As an example, the operations for identifying the motion vector (MV) and reference picture for the luma CB do not need to be repeated to identify the MV and reference picture for the chroma block. Rather, the MV for the luma CB 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 can be the same for the luma CB and the chroma CB.

[0247] Video encoder 200 represents an example of a device configured to encode video data, the device comprising: a memory configured to store the video data; and one or more processing units implemented in circuitry and configured to perform any one or combination of the examples described in this disclosure.

[0248] In one example, the video encoder 200 may determine that applying luma partitioning to a chroma region within a chroma component corresponding to the luma partition produces a chroma block having a size less than a threshold; determine a SCIPU based on the chroma region (e.g., SCIPU equals the chroma region); and encode the video data based on the determination of the SCIPU. As an example, the video encoder 200 may determine a manner of splitting the chroma region based on the determination of the SCIPU, and encode the chroma block based on the determination of the manner of splitting the chroma region.

[0249] In one example, the video encoder 200 may determine that the video data is formatted according to a 4:4:4 video coding format, determine to disable the SCIPU for the video data having the 4:4:4 video coding format, and encode the video data having the 4:4:4 video coding format based on the determination to disable the SCIPU. In another example, the video encoder 200 may determine that the video data is formatted according to monochrome sampling, determine to disable the SCIPU for the video data having monochrome sampling, and encode the video data having monochrome sampling based on the determination to disable the SCIPU.

[0250] In one example, the video encoder 200 may encode the video data in a manner such that the splitting of at least one of the luma or chroma components does not produce at least one of the luma blocks or chroma blocks of 2xN size. In one example, where a single tree is used to split the luma and chroma components, the video encoder 200 may encode the video data in a manner such that intra mode is disabled for 4xN luma blocks.

[0251] In one example, the video encoder 200 may determine that the chroma width of the chroma block is 8, determine the splitting of the luma component into a ternary tree, determine the SCIPU based on the chroma block (e.g., SCIPU is equal to the chroma block), and encode the video data based on the determination of the SCIPU. For example, the video encoder 200 may determine the manner in which the chroma components are split based on the determination of the SCIPU, and encode the chroma block based on the determination of the manner in which the chroma regions are split.

[0252] In one example, the video encoder 200 may determine that the chroma width of the chroma block is 4, determine that the splitting of the luma component is vertical, determine the SCIPU based on the chroma block (e.g., SCIPU equals the chroma block), and encode the video data based on the determination of the SCIPU. For example, the video encoder 200 may determine a manner to split the chroma components based on the determination of the SCIPU, and encode the chroma block based on the determination of the manner to split the chroma region.

[0253] In one example, the video encoder 200 may determine whether splitting of chroma regions in chroma components is enabled in an intra SCIPU, and encode the chroma regions based on the determination. In one example, the video encoder 200 may determine splitting of a luma block, determine split candidates for chroma regions in an intra SCIPU corresponding to the luma block, and encode the chroma regions and the luma block based on the determined splitting of the luma block and the split candidates for the chroma regions. In one example, the video encoder 200 may determine one or more of splitting of the luma region, a size of a minimum luma block, and a size of a minimum chroma block of a partition, determine whether the chroma block is a SCIPU or whether the chroma block is an inter SCIPU or an intra SCIPU, and decode the chroma block based on the determination of whether the chroma block is a SCIPU or whether the chroma block is an inter SCIPU or an intra SCIPU.

[0254] Figure 16 is a block diagram illustrating an example video decoder 300 that may perform the techniques of this disclosure. Figure 16This is provided for purposes of explanation and does not limit the techniques generally illustrated and described in this disclosure. For purposes of explanation, this disclosure describes a video decoder 300 based on techniques of JEM, VVC, and HEVC. However, the techniques of this disclosure can be performed by video coding devices configured for other video coding standards.

[0255] exist Figure 16 In the example of FIG, the video decoder 300 includes a coded picture buffer (CPB) memory 320, an entropy decoding unit 302, a prediction processing unit 304, an inverse quantization unit 306, an inverse transform processing unit 308, a reconstruction unit 310, a filter unit 312, and a decoded picture buffer (DPB) 314. Any or all of the CPB memory 320, the entropy decoding unit 302, the prediction processing unit 304, the inverse quantization unit 306, the inverse transform processing unit 308, the reconstruction unit 310, the filter unit 312, and the DPB 314 may be implemented in one or more processors or in processing circuitry. Furthermore, the video decoder 300 may include additional or alternative processors or processing circuitry to perform these and other functions.

[0256] The prediction processing unit 304 includes a motion compensation unit 316 and an intra prediction unit 318. The prediction processing unit 304 may include an addition unit that performs prediction according to other prediction modes. As an example, the prediction processing unit 304 may include a palette unit, an intra block copy unit (which may form part of the motion compensation unit 316), an affine unit, a linear model (LM) unit, etc. In other examples, the video decoder 300 may include more, fewer, or different functional components.

[0257] CPB memory 320 may store video data, such as an encoded video bitstream, to be decoded by components of video decoder 300. For example, the video bitstream may be encoded from computer readable medium 110 ( Figure 1) obtains video data stored in CPB memory 320. CPB memory 320 may include a CPB that stores coded video data (e.g., syntax elements) from a coded video bitstream. Furthermore, CPB memory 320 may store video data other than syntax elements for decoded pictures, such as temporary data representing outputs from various units of video decoder 300. DPB 314 typically stores decoded pictures, which video decoder 300 may output and / or use as reference video data when decoding subsequent data or pictures in the coded video bitstream. CPB memory 320 and DPB 314 may be formed from any of a variety of memory devices, such as DRAM, including SDRAM, MRAM, RRAM, or other types of memory devices. CPB memory 320 and DPB 314 may be provided by the same memory device or separate memory devices. In various examples, CPB memory 320 may be on-chip with other components of video decoder 300, or off-chip relative to those components.

[0258] Additionally or alternatively, in some examples, video decoder 300 may retrieve the video from memory 120 ( Figure 1 ) to retrieve the decoded video data. That is, memory 120 may 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 may store instructions to be executed by video decoder 300.

[0259] Explained in Figure 16 The various units shown in FIG. 300 help understand the operations performed by the video decoder 300. These units can be implemented as fixed function circuits, programmable circuits, or a combination thereof. Figure 15 , fixed-function circuits refer to circuits that provide specific functions and are pre-set with respect to the 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 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 the 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 performed by the fixed-function circuits are generally immutable. In some examples, one or more of these units may be different circuit blocks (fixed-function or programmable), and in some examples, one or more units may be integrated circuits.

[0260] The video decoder 300 may include an ALU, an EFU, digital circuits, analog circuits, and / or a programmable core formed by programmable circuits. In examples where the operation of the video decoder 300 is performed by software executed on the programmable circuits, on-chip or off-chip memory may store instructions (e.g., object code) of the software that the video decoder 300 receives and executes.

[0261] The entropy decoding unit 302 may receive the encoded video data from the CPB and perform entropy decoding on the video data to reproduce the syntax elements. The prediction processing unit 304, the inverse quantization unit 306, the inverse transform processing unit 308, the reconstruction unit 310, and the filter unit 312 may generate decoded video data based on the syntax elements extracted from the bitstream.

[0262] Typically, the video decoder 300 reconstructs a picture block by block. The video decoder 300 may perform a reconstruction operation on each block individually (wherein a block currently being reconstructed (ie, decoded) may be referred to as a "current block").

[0263] The entropy decoding unit 302 may entropy decode syntax elements defining the quantized transform coefficients of the quantized transform coefficient block, as well as transform information such as a quantization parameter (QP) and / or a transform mode indication. The inverse quantization unit 306 may use the QP associated with the quantized transform coefficient block to determine a degree of quantization and, similarly, determine a degree of inverse quantization for the inverse quantization unit 306 to apply. The inverse quantization unit 306 may, for example, perform a bitwise left shift operation to inverse quantize the quantized transform coefficients. The inverse quantization unit 306 may thereby form a transform coefficient block comprising the transform coefficients.

[0264] After the inverse quantization unit 306 forms the transform coefficient block, the inverse transform processing unit 308 may apply one or more inverse transforms to the transform coefficient block to generate a residual block associated with the current block. For example, the inverse transform processing unit 308 may apply an inverse DCT, an inverse integer transform, an inverse Karhunen-Loeve transform (KLT), an inverse rotational transform, an inverse directional transform, or another inverse transform to the coefficient block.

[0265] In addition, prediction processing unit 304 generates a prediction block based on the prediction information syntax element entropy decoded by entropy decoding unit 302. For example, if the prediction information syntax element indicates that the current block is inter-predicted, motion compensation unit 316 may generate a prediction block. In this case, the prediction information syntax element may indicate a reference picture in DPB 314 from which to retrieve the reference block, and a motion vector that identifies the position of the reference block in the reference picture relative to the position of the current block in the current picture. Motion compensation unit 316 may generally generate a prediction block in the same manner as described for motion compensation unit 224 ( Figure 15) is performed in a manner substantially similar to that described in the foregoing.

[0266] As another example, if the prediction information syntax element indicates that the current block is intra-predicted, the intra-prediction unit 318 may generate a prediction block according to the intra-prediction mode indicated by the prediction information syntax element. Again, the intra-prediction unit 318 may generally generate a prediction block in the same manner as described with respect to the intra-prediction unit 226 ( Figure 15 ) is performed in a manner substantially similar to that described in the preceding claims. The intra prediction unit 318 may retrieve data for neighboring samples of the current block from the DPB 314. When decoding a block, the intra prediction unit 318 may enable and disable the SCIPU based on the chroma subsampling format of the video data as described in this disclosure.

[0267] The reconstruction unit 310 may reconstruct the current block using the prediction block and the residual block. For example, the reconstruction unit 310 may add samples of the residual block to corresponding samples of the prediction block to reconstruct the current block.

[0268] The filter unit 312 may perform one or more filter operations on the reconstructed block. For example, the filter unit 312 may perform a deblocking operation to reduce blocking artifacts along the edges of the reconstructed block. The operations of the filter unit 312 may not necessarily be performed in all examples.

[0269] The video decoder 300 may store the reconstructed blocks in the DPB 314. As discussed above, the DPB 314 may provide reference information (such as samples of the current picture for intra prediction and previously decoded pictures for subsequent motion compensation) to the prediction processing unit 304. In addition, the video decoder 300 may output decoded pictures from the DPB 314 for use in other video processing operations such as Figure 1 Subsequent presentation on a display device such as display device 118.

[0270] In this manner, video decoder 300 represents an example of a device configured to decode video data, the device comprising: a memory configured to store the video data; and one or more processing units implemented in circuitry and configured to perform any one or combination of the examples described in this disclosure.

[0271] In one example, the video decoder 300 may perform the following operations: determining that applying the luma partition to the chroma region within the chroma component corresponding to the luma partition produces a chroma block having a size less than a threshold; determining the SCIPU based on the chroma region (e.g., SCIPU is equal to the chroma region); and decoding the video data based on the determination of the SCIPU. As an example, the video decoder 300 may determine a manner of splitting the chroma region based on the determination of the SCIPU, and decode the chroma block based on the determination of the manner of splitting the chroma region.

[0272] In one example, the video decoder 300 may determine that the video data is formatted according to a 4:4:4 video coding format, determine to disable the SCIPU for the video data having the 4:4:4 video coding format, and decode the video data having the 4:4:4 video coding format based on the determination to disable the SCIPU. In another example, the video decoder 300 may determine that the video data is formatted according to monochrome sampling, determine to disable the SCIPU for the video data having monochrome sampling, and decode the video data having monochrome sampling based on the determination to disable the SCIPU.

[0273] In one example, the video decoder 300 may decode the video data in a manner such that the splitting of at least one of the luma or chroma components does not produce at least one of the luma or chroma blocks of 2xN size. In one example, where a single tree is used to split the luma and chroma components, the video decoder 300 may decode the video data in a manner such that intra mode is disabled for 4xN luma blocks.

[0274] In one example, the video decoder 300 may determine that the chroma width of the chroma block is 8, determine the splitting of the luma component into a ternary tree, determine the SCIPU based on the chroma block (e.g., SCIPU is equal to the chroma block), and decode the video data based on the determination of the SCIPU. For example, the video decoder 300 may determine how to split the chroma region (e.g., samples of the chroma component) based on the determination of the SCIPU, and decode the chroma block based on the determination of the way to split the chroma region.

[0275] In one example, the video decoder 300 may determine that the chroma width of the chroma block is 4, determine that the splitting of the luma component is vertical, determine the SCIPU based on the chroma block (e.g., SCIPU is equal to the chroma block), and decode the video data based on the determination of the SCIPU. For example, the video decoder 300 may determine a manner of splitting the chroma components based on the determination of the SCIPU, and decode the chroma block based on the determination of the manner of splitting the chroma region.

[0276] In one example, the video decoder 300 may determine that splitting of chroma regions in chroma components is enabled in an intra SCIPU, and decode the chroma regions based on the determination. In one example, the video decoder 300 may determine splitting of a luma block, determine split candidates for chroma regions in an intra SCIPU corresponding to the luma block, and decode the chroma regions and the luma block based on the determined splitting of the luma block and the split candidates for the chroma regions. In one example, the video decoder 300 may determine one or more of splitting of the luma region, a size of a minimum luma block, and a size of a minimum chroma block of a partition, determine whether the chroma block is a SCIPU or whether the chroma block is an inter SCIPU or an intra SCIPU, and decode the chroma block based on the determination of whether the chroma block is a SCIPU or whether the chroma block is an inter SCIPU or an intra SCIPU.

[0277] Figure 17 1 is a flowchart illustrating an example method for encoding a current block. The current block may include a current CU. Although with respect to the video encoder 200 ( Figure 1 and 14), but it will be appreciated that other devices may be configured to perform the same Figure 17 A similar approach to the one in the previous section.

[0278] In this example, the video encoder 200 initially predicts a current block (350). For example, the video encoder 200 may form a prediction block for the current block. The video encoder 200 may then calculate a residual block for the current block (532). To calculate the residual block, the video encoder 200 may calculate the difference between the original, unencoded block and the prediction block for the current block. The video encoder 200 may then transform and quantize the coefficients of the residual block (354). Next, the video encoder 200 may scan the quantized transform coefficients of the residual block (356). During or after the scan, the video encoder 200 may entropy encode the coefficients (358). For example, the video encoder 200 may encode the coefficients using CAVLC or CABAC. The video encoder 200 may then output the entropy coded data for the block (360).

[0279] Figure 18 is a flowchart illustrating an example method for decoding a current block of video data. The current block may include a current CU. Although with respect to the video decoder 300 ( Figure 1 and 15 ) is described, but it should be understood that other devices may be configured to perform the same Figure 18 A similar approach to the one in the previous section.

[0280] The video decoder 300 may receive entropy-coded data for a current block (e.g., entropy-coded prediction information and entropy-coded data for coefficients of a residual block corresponding to the current block) (370). The video decoder 300 may entropy decode the entropy-coded data to determine prediction information for the current block and reproduce coefficients of the residual block (372). The video decoder 300 may predict the current block (374), e.g., calculating a prediction block for the current block using an intra-frame or inter-frame prediction mode as indicated by the prediction information for the current block. The video decoder 300 may then inverse scan the reproduced coefficients (376) to create a block of quantized transform coefficients. The video decoder 300 may then inverse quantize and inverse transform the coefficients to produce a residual block (378). Finally, the video decoder 300 may decode the current block by combining the prediction block and the residual block (380).

[0281] Figure 19 is a flowchart illustrating an example method for decoding a current block of video data. The current block may include a current CU. Although with respect to the video decoder 300 ( Figure 1 and 15 ) is described, but it should be understood that other devices may be configured to perform the same Figure 19 A similar approach to the one in the previous section.

[0282] The video decoder 300 determines 400 that a block of video data is formatted according to a 4:4:4 video coding format. Because the block is coded in the 4:4:4 video coding format, the luma component, the first chroma component, and the second chroma component of the block may all have the same size, meaning that the chroma components are not subsampled relative to the luma component. The block of video data may be, for example, a CTU. The luma component of the block may be a luma CTB of the CTU; the first chroma component of the block may be a first chroma CTB of the CTU; and the second chroma component of the block may be a second chroma CTB of the CTU.

[0283] Video decoder 300 determines whether a block of video data is encoded in an intra-prediction mode (402). Even if encoded in an intra-prediction mode, the block of video data may be included in an inter-coded slice because an inter-coded slice may include both intra-coded blocks and inter-coded blocks.

[0284] The video decoder 300 determines to disable SCIPU for the block in response to determining that the block has a 4:4:4 video coding format (404). For example, the video decoder 300 can determine that the block is in a 4:4:4 video coding format based on syntax signaled at a slice level or other higher-level syntax data. In response to determining to disable SCIPU for the block, the video decoder 300 can, for example, determine that the luma component, the first chroma component, and the second chroma component have the same partitioning structure. In the same partitioning structure, the first chroma component and the second chroma component can be less than 16 samples. The first chroma component and the second chroma component can also have a vertically narrow shape, which means that the first chroma component and the second chroma component can be less than 16 samples and have a height greater than a width.

[0285] The video decoder 300 decodes the block of video data based on the determination to disable the SCIPU (406). To decode the block of video data based on the determination to disable the SCIPU, the video decoder 300 may, for example, determine that both the first chroma component of the block and the second chroma component of the block have the same size as the luma component of the block, intra-predict the luma component of the block, intra-predict the first chroma component of the block, and intra-predict the second chroma component of the block.

[0286] Video decoder 300 outputs decoded video data (408) including a decoded version of the block. Video decoder 300 may, for example, output the decoded video data for display or storage. Video decoder 300 may, for example, store the video data for transmission, future display, or use in decoding other blocks of video data. In some examples, Figure 19 The described techniques may be performed by a video decoding loop of a video encoder, in which case the output decoded video data may be used to determine how to encode other blocks of video data.

[0287] In one example, the video decoder 300 further performs the following operations: determining that a second block of video data is formatted according to a non-4:4:4 video coding format; determining that the second block of video data is encoded in an intra-frame prediction mode; determining that SCIPU is enabled for the block in response to determining that the block has a non-4:4:4 video coding format; decoding the second block of video data based on the determination regarding enabling SCIPU; and outputting decoded video data including a decoded version of the second block. The luma component of the second block may have a different size than the first chroma component of the second block and the second chroma component of the second block. In response to determining that SCIPU is enabled for the second block, the video decoder 300 may determine that the luma component of the second block, the first chroma component of the second block, and the second chroma component of the second block have different partitioning structures.

[0288] To decode the second block of video data based on the determination that SCIPU is enabled, the video decoder 300 may intra-predict the luma component of the second block, intra-predict the first chroma component of the second block, and intra-predict the second chroma component of the second block. The luma component of the second block may have a size of 4xN, where 4 is the width of the luma component of the second block and N is the height of the luma component of the second block. However, since SCIPU is enabled, the first chroma component of the second block may have a width greater than or equal to 4, and the second chroma component of the second block may have a width greater than or equal to 4, even if the second block is decoded in a non-4:4:4 format.

[0289] One or more examples are described below. The example techniques can be used alone or in combination.

[0290] Example 1. A method for decoding video data, the method comprising: determining that applying a luma partition to a chroma region within a chroma component corresponding to the luma partition produces a chroma block having a size less than a threshold; determining a minimum chroma intra-frame prediction unit (SCIPU) based on the chroma region; and decoding the video data based on the determination of the SCIPU.

[0291] Example 2. A method for decoding video data, the method comprising: determining that the video data is formatted according to a 4:4:4 video decoding format, determining to disable a minimum chroma intra prediction unit (SCIPU) for the video data having the 4:4:4 video decoding format; and decoding the video data having the 4:4:4 video decoding format based on the determination regarding disabling the SCIPU.

[0292] Example 3. A method for decoding video data, the method comprising: determining that the video data is formatted according to monochrome sampling; determining to disable a minimum chroma intra-frame prediction unit (SCIPU) for the video data having the monochrome sampling; and decoding the video data having the monochrome sampling based on the determination about disabling the SCIPU.

[0293] Example 4. A method of decoding video data, the method comprising any one or combination of Examples 1-3.

[0294] Example 5. A method of decoding video data, the method comprising: decoding the video data in a manner such that splitting of at least one of a luma component or a chroma component does not produce at least one of a 2xN luma block or a 2xN chroma block.

[0295] Example 6. A method according to Example 5, wherein decoding the video data includes: when using separate decoding trees to split the luminance component and the chrominance component, decoding the video data in a manner such that the splitting of at least one of the luminance component or the chrominance component does not produce at least one of a 2xN luminance block or a 2xN chrominance block.

[0296] Example 7. The method of any one of Examples 5 and 6, wherein decoding the video data comprises: determining to disable ternary tree (TT) splitting based on the block width being equal to 8.

[0297] Example 8. The method of any one of Examples 5-7, wherein decoding the video data comprises: determining to disable vertical splitting based on the block width being equal to 4.

[0298] Example 9. A method of coding video data, the method comprising coding the video data in a manner such that intra mode is disabled for 4xN luma blocks if a single tree is used to partition luma and chroma components.

[0299] Example 10. A method for decoding video data, the method comprising: determining a chroma width of a chroma block to be 8; determining a split of a luminance component into a ternary tree; determining a minimum chroma intra prediction unit (SCIPU) based on the chroma block; and decoding the video data based on the determination of the SCIPU.

[0300] Example 11. A method for decoding video data, the method comprising: determining that the chroma width of a chroma block is 4; determining that the splitting of the luminance component is vertical; determining a minimum chroma intra-frame prediction unit (SCIPU) based on the chroma block; and decoding the video data based on the determination of the SCIPU.

[0301] Example 12. A method of decoding video data, the method comprising: determining to enable splitting of a chroma region in a chroma component in an intra minimum chroma intra prediction unit (SCIPU); and decoding the chroma region based on the determination.

[0302] Example 13. The method of Example 12, wherein determining to enable splitting of the chroma region in the chroma component comprises performing splitting that results in a minimum sub-block size that satisfies a block size constraint.

[0303] Example 14. The method of Example 13, wherein performing the splitting comprises performing vertical splitting when the chroma region of the SCIPU within the frame is 8xN.

[0304] Example 15. A method according to any one of Examples 13 and 14, wherein performing the splitting includes: performing horizontal splitting when the chroma area of ​​the SCIPU within the frame is 8x4.

[0305] Example 16. A method according to any one of Examples 13-15, wherein performing the splitting includes: when the chroma area of ​​the SCIPU within the frame is 8xN and N is greater than 8, performing at least one of vertical splitting, horizontal splitting, or ternary tree horizontal splitting.

[0306] Example 17. A method according to any one of Examples 12-16, wherein determining to enable splitting of the chroma region in the chroma component includes: when the chroma region of the intra-frame SCIPU is 4x8, determining to enable horizontal binary tree splitting.

[0307] Example 18. A method according to any one of Examples 12-17, wherein determining to enable splitting of the chroma region in the chroma component includes: when the chroma region of the intra-frame SCIPU is 4xN, determining to enable horizontal binary tree splitting.

[0308] Example 19. A method according to any one of Examples 12-17, wherein determining to enable splitting of the chroma area in the chroma component includes: when the chroma area of ​​the SCIPU within the frame is 4xN and N is greater than 8, determining to enable horizontal splitting including binary tree horizontal splitting and ternary tree horizontal splitting.

[0309] Example 20. A method for decoding video data, the method comprising: determining a split of a luma block; determining split candidates for a chroma region in an intra-frame minimum chroma intra-frame prediction unit (SCIPU) corresponding to the luma block; and decoding the chroma region and the luma block based on the determined split of the luma block and the split candidates for the chroma region.

[0310] Example 21. The method of Example 20, wherein determining the split candidate comprises determining that chroma splitting is not allowed based on the luma block not being split.

[0311] Example 22. The method of any one of Examples 20 and 21, wherein determining the split candidate comprises determining that a chroma split cannot be orthogonal to a luma split direction.

[0312] Example 23. A method according to Example 22, wherein determining that the chroma splitting cannot be orthogonal to the luminance splitting direction includes: determining that horizontal splitting is not allowed for the SCIPU within the chroma frame based on that the splitting of the luminance block is vertical; or determining that vertical splitting is not allowed for the SCIPU within the chroma frame based on that the splitting of the luminance block is horizontal.

[0313] Example 24. A method for decoding video data, the method comprising: determining one or more of the splitting of a luminance region, the size of a minimum luminance block, and the size of a minimum chroma block of a partition; determining, based on the determination, whether a chroma block is a minimum chroma intra-frame prediction unit (SCIPU) and whether the chroma block is at least one of an inter-frame SCIPU or an intra-frame SCIPU; and decoding the chroma block based on the determination of whether the chroma block is the SCIPU or whether the chroma block is at least one of the inter-frame SCIPU or the intra-frame SCIPU.

[0314] Example 25. The method according to Example 24, wherein determining whether the chroma block is the SCIPU comprises determining whether the chroma block is the SCIPU based on the size of the minimum luminance block and the size of the minimum chroma block of the partition being less than a threshold.

[0315] Example 26. According to the method described in any one of Examples 24 and 25, for the chroma block that is the SCIPU, the chroma block is determined to be the intra-frame SCIPU based on the size of the minimum luminance block of the SCIPU in the intra-frame slice or the region being smaller than the minimum size enabled for the inter-frame block.

[0316] Example 27. The method according to any one or a combination of Examples 1-26.

[0317] Example 28. A method according to any one or a combination of Examples 1-26, wherein decoding includes decoding, and wherein decoding includes reconstructing the video data.

[0318] Example 29. A method according to any one or a combination of Examples 1-26, wherein decoding includes encoding, and wherein encoding includes signaling the video data.

[0319] Example 30. A device for decoding video data, the device comprising: a memory configured to store video data; and a video decoder coupled to the memory and comprising at least one of a fixed-function circuit or a programmable circuit, wherein the video decoder is configured to perform the method described in any one or a combination of Examples 1-26.

[0320] Example 31. The apparatus of Example 30, wherein the video decoder comprises a video decoder, and wherein the video decoder is configured to reconstruct the video data.

[0321] Example 32. The apparatus of Example 30, wherein the video decoder comprises a video encoder, and wherein the video encoder is configured to signal the video data.

[0322] Example 33. The apparatus of any of Examples 30-32, further comprising: a display configured to display the decoded video data.

[0323] Example 34. The device of any of Examples 30-33, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

[0324] Example 35. A computer-readable storage medium having instructions stored thereon, the instructions, when executed, causing one or more processors to perform the method according to any one or a combination of Examples 1-26.

[0325] Example 36. An apparatus for decoding video data, the apparatus comprising means for performing the method according to any one or a combination of Examples 1-26.

[0326] It will be appreciated that, depending on the examples, certain actions or events of any of the techniques described herein may be performed in a different order, may be added, combined, or omitted entirely (e.g., not all described actions or events are necessary to implement the techniques). Furthermore, in some examples, actions or events may be performed concurrently rather than sequentially, for example, through multithreading, interrupt handling, or multiple processors.

[0327] In one or more examples, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted through a computer-readable medium as one or more instructions or codes and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media, which corresponds to tangible media such as data storage media or communication media, including any media that facilitates the transfer of a computer program from one place to another, for example, according to a communication protocol. In this manner, computer-readable media may generally correspond to (1) non-transitory tangible computer-readable storage media, or (2) communication media such as signals or carrier waves. Data storage media may be any available media that can be accessed by one or more computers or one or more processors to obtain instructions, codes, and / or data structures for implementing the techniques described in this disclosure. A computer program product may include computer-readable media.

[0328] By way of example and not limitation, such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, flash memory, or any other 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. In addition, any connection is appropriately referred to as a computer-readable medium. For example, if instructions are transmitted from a website, server or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) or wireless technology (e.g., infrared, radio and microwave), the coaxial cable, fiber optic cable, twisted pair, DSL or wireless technology (e.g., infrared, radio and microwave) is included in the definition of medium. However, it should be understood that computer-readable storage media and data storage media do not include connections, carrier waves, signals or other temporary media, but are instead directed to non-temporary tangible storage media. As used herein, disks and optical disks include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks and Blu-ray discs, wherein disks typically copy data magnetically, while optical discs use lasers to copy data optically. Combinations of the above should also be included within the scope of computer-readable media.

[0329] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Thus, the terms "processor" and "processing circuitry" as used herein may refer to any of the aforementioned structures or any other structure suitable for implementing the techniques described herein. Additionally, in some aspects, the functionality described herein may be provided within dedicated hardware and / or software modules configured for encoding and decoding, or incorporated into a combined codec. Furthermore, the techniques may be implemented entirely in one or more circuits or logic elements.

[0330] The techniques of the present 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 chipset). Various components, modules, or units are described in this disclosure to emphasize functional aspects of a device configured to perform the disclosed techniques, but do not necessarily need to be implemented by different hardware units. Specifically, as described above, the various units can be combined in a codec hardware unit, or provided by a collection of interoperable hardware units (including one or more processors as described above) in combination with appropriate software and / or firmware.

[0331] 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: determining that the block of video data is formatted according to a 4:4:4 video coding format; determining that the block of the video data is encoded in an intra-prediction mode; responsive to determining that the block has the 4:4:4 video coding format and determining that the block of video data is encoded in the intra-prediction mode, determining to disable a minimum chroma intra prediction unit (SCIPU) for the block; In response to determining that the SCIPU is disabled for the block, decoding the block without restricting a partitioning structure for the block; and Decoded video data including a decoded version of the block is output.

2. The method according to claim 1, wherein The block has a luma component, a first chroma component, and a second chroma component, and wherein the luma component, the first chroma component, and the second chroma component have the same size.

3. The method according to claim 2, wherein: The same size is less than 16 samples.

4. The method according to claim 2, further comprising: In response to determining that the SCIPU is disabled for the block, it is determined that the luma component, the first chroma component, and the second chroma component have the same partitioning structure.

5. The method according to claim 1, wherein The block of the video data encoded in the intra-prediction mode is included in an inter-coded slice.

6. The method according to claim 1, wherein Decoding the block of the video data based on the determination to disable the SCIPU includes: performing intra-frame prediction on the luminance component of the block; performing intra-frame prediction on a first chroma component of the block; and A second chroma component of the block is intra-predicted, wherein both the first chroma component of the block and the second chroma component of the block have the same size as the luma component of the block.

7. The method according to claim 6, wherein: The block of video data comprises a coding tree unit (CTU), the luma component of the block comprises a luma coding unit of the CTU, the first chroma component of the block comprises a first chroma coding unit of the CTU, and the second chroma component of the block comprises a second chroma coding unit of the CTU.

8. The method according to claim 7, wherein: The first chroma decoding unit and the second chroma decoding unit are smaller than 4x4.

9. The method according to claim 1, further comprising: determining that a second block of the video data is formatted according to a non-4:4:4 video coding format; determining that the second block of the video data is encoded in an intra-prediction mode; responsive to determining that the block has the non-4:4:4 video coding format and determining that the second block of the video data is encoded in the intra-prediction mode, determining to enable the SCIPU for the block; decoding the second block of the video data without using a chroma prediction unit that is smaller than the size of the SCIPU; and Decoded video data including a decoded version of the second block is output.

10. The method according to claim 9, wherein: The luma component of the second block has a different magnitude from the first chroma component of the second block and the second chroma component of the second block.

11. The method according to claim 9, further comprising: In response to determining that the SCIPU is enabled for the second block, it is determined that a first chroma component of the second block and a second chroma component of the second block have a different partitioning structure than a luma component of the second block.

12. The method according to claim 9, wherein Decoding the second block of the video data based on the determination to enable the SCIPU includes: performing intra prediction on the luminance component of the second block; performing intra-frame prediction on the first chrominance component of the second block; and A second chroma component of the second block is intra-predicted, wherein the luma component of the second block has a size of 4xN, where 4 is a width of the luma component of the second block and N is a height of the luma component of the second block, and wherein the first chroma component of the second block has a width greater than or equal to 4, and the second chroma component of the second block has a width greater than or equal to 4.

13. The method according to claim 12, wherein: N is equal to 2.

14. The method according to claim 1, wherein The decoding method is performed as part of a video encoding operation.

15. A device for decoding video data, the device comprising: a memory configured to store video data; One or more processors implemented in circuitry and configured to: determining that the block of video data is formatted according to a 4:4:4 video coding format; determining that the block of the video data is encoded in an intra-prediction mode; responsive to determining that the block has the 4:4:4 video coding format and determining that the block of video data is encoded in the intra-prediction mode, determining to disable a minimum chroma intra prediction unit (SCIPU) for the block; In response to determining that the SCIPU is disabled for the block, decoding the block without restricting a partitioning structure for the block; and Decoded video data including a decoded version of the block is output.

16. The apparatus according to claim 15, wherein The block has a luma component, a first chroma component, and a second chroma component, and wherein the luma component, the first chroma component, and the second chroma component have the same size.

17. The apparatus according to claim 16, wherein The same size is less than 16 samples.

18. The apparatus according to claim 16, wherein The one or more processors are further configured to: In response to determining that the SCIPU is disabled for the block, it is determined that the luma component, the first chroma component, and the second chroma component have the same partitioning structure.

19. The apparatus according to claim 15, wherein The block of the video data encoded in the intra-prediction mode is included in an inter-coded slice.

20. The apparatus of claim 15, wherein: To decode the block of the video data based on the determination to disable the SCIPU, the one or more processors are further configured to: performing intra-frame prediction on the luminance component of the block; performing intra-frame prediction on a first chrominance component of the block; as well as A second chroma component of the block is intra-predicted, wherein both the first chroma component of the block and the second chroma component of the block have the same size as the luma component of the block.

21. The apparatus according to claim 20, wherein The block of video data comprises a coding tree unit (CTU), the luma component of the block comprises a luma coding unit of the CTU, the first chroma component of the block comprises a first chroma coding unit of the CTU, and the second chroma component of the block comprises a second chroma coding unit of the CTU.

22. The apparatus according to claim 21, wherein The first chroma decoding unit and the second chroma decoding unit are smaller than 4x4.

23. The apparatus of claim 15, wherein: The one or more processors are further configured to: determining that a second block of the video data is formatted according to a non-4:4:4 video coding format; determining that the second block of the video data is encoded in an intra-prediction mode; responsive to determining that the block has the non-4:4:4 video coding format and determining that the second block of the video data is encoded in the intra-prediction mode, determining to enable the SCIPU for the block; decoding the second block of the video data without using a chroma prediction unit that is smaller than the size of the SCIPU; and Decoded video data including a decoded version of the second block is output.

24. The apparatus according to claim 23, wherein The luma component of the second block has a different magnitude from the first chroma component of the second block and the second chroma component of the second block.

25. The apparatus of claim 23, wherein: The one or more processors are further configured to: In response to determining that the SCIPU is enabled for the second block, it is determined that a first chroma component of the second block and a second chroma component of the second block have a different partitioning structure than a luma component of the second block.

26. The apparatus of claim 23, wherein: To decode the second block of the video data based on the determination to enable the SCIPU, the one or more processors are further configured to: performing intra prediction on the luminance component of the second block; performing intra prediction on the first chrominance component of the second block; as well as A second chroma component of the second block is intra-predicted, wherein the luma component of the second block has a size of 4xN, where 4 is a width of the luma component of the second block and N is a height of the luma component of the second block, and wherein the first chroma component of the second block has a width greater than or equal to 4, and the second chroma component of the second block has a width greater than or equal to 4.

27. The apparatus of claim 26, wherein: N is equal to 2.

28. The apparatus of claim 15, wherein: The device is configured to decode the video data as part of a video encoding operation.

29. The apparatus of claim 15, wherein: The apparatus comprises a wireless communication device further comprising a receiver configured to receive encoded video data.

30. The apparatus of claim 29, wherein: The wireless communication device comprises a telephone handset, and wherein the receiver is configured to demodulate a signal comprising the video data in accordance with a wireless communication standard.

31. The apparatus of claim 15, further comprising: A display configured to display the decoded video data.

32. The apparatus of claim 15, wherein: The device includes one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

33. A computer-readable storage medium storing instructions that, when executed by one or more processors, cause the one or more processors to: determining that the block of video data is formatted according to a 4:4:4 video coding format; determining that the block of the video data is encoded in an intra-prediction mode; responsive to determining that the block has the 4:4:4 video coding format and determining that the block of video data is encoded in the intra-prediction mode, determining to disable a minimum chroma intra prediction unit (SCIPU) for the block; In response to determining that the SCIPU is disabled for the block, decoding the block without restricting a partitioning structure for the block; and Decoded video data including a decoded version of the block is output.

34. An apparatus for decoding video data, the apparatus comprising: a unit for determining whether the block of video data is formatted according to a 4:4:4 video coding format; means for determining that the block of the video data is encoded in an intra-prediction mode; means for determining to disable a minimum chroma intra prediction unit (SCIPU) for the block in response to determining that the block has the 4:4:4 video coding format and determining that the block of video data is encoded in the intra prediction mode; means for decoding the block without restricting a partitioning structure for the block in response to determining that the SCIPU is disabled for the block; as well as Means for outputting decoded video data comprising a decoded version of the block.

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