Intra-block copy prediction restrictions in video coding

Abstract

An example method includes: determining, for each corresponding coding block of a plurality of coding blocks of a current coding tree unit (CTU) of video data in a current picture of video data, a corresponding search area of ​​a plurality of corresponding search areas, wherein at least one search area of ​​the plurality of search areas includes samples of the current picture located outside the current CTU, and wherein at least one search area of ​​the plurality of search areas does not include samples of the current picture located outside the current CTU; selecting, for each corresponding coding block and from within the corresponding search area for the corresponding coding block, a corresponding predictor block of a plurality of predictor blocks; and reconstructing samples of each corresponding coding block based on samples included in the corresponding predictor block of the plurality of predictor blocks.

Description

[0001] This application claims priority to U.S. Application No. 16 / 663,033, filed on October 24, 2019, which claims the benefit of U.S. Provisional Application No. 62 / 751,585, filed on October 27, 2018, the entire contents of which are incorporated herein by reference. Technical Field

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

[0003] Digital video capabilities can be incorporated into a wide range of devices, including digital televisions, digital direct broadcast systems, wireless broadcast systems, personal digital assistants (PDAs), laptop or desktop computers, tablet computers, e-book readers, digital cameras, digital recording devices, digital media players, video game devices, video game consoles, cellular or satellite wireless telephones, so-called "smart phones", video teleconferencing devices, video streaming devices, etc. 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), High Efficiency Video Coding (HEVC) standards, ITU-T H.265 / High Efficiency Video Coding (HEVC), and extensions of these standards. By implementing such video coding techniques, video devices can more efficiently send, receive, encode, decode and / or store digital video information.

[0004] Video coding techniques include spatial (intra-picture) prediction and / or temporal (inter-picture) prediction to reduce or eliminate 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 predictions of 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 predictions of reference samples in neighboring blocks in the same picture or temporal predictions of 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

[0005] In general, the present disclosure describes techniques for improving decoding efficiency and / or memory requirements for decoded video data using a current picture reference (CPR) / intra-block copy (IBC) mode. For example, a video decoder (e.g., a video encoder or a video decoder) may utilize different search areas for each decoding block of a coding tree unit (CTU) of a current picture. Specifically, at least some of the search areas may include samples of the current picture that are outside the current CTU, and at least some of the search areas may not include samples of the current picture that are outside the current CTU. The techniques of the present disclosure may be used with screen content decoding, including support for possible high bit depths (greater than 8 bits), different chroma sampling formats (such as 4:4:4, 4:2:2, 4:2:0, 4:0:0), and other techniques.

[0006] As an example, a method includes: determining, for each corresponding decoding block in a plurality of decoding blocks of a current decoding tree unit (CTU) of video data in a current picture of video data, a corresponding search area among a plurality of corresponding search areas, wherein the search areas among the plurality of search areas are different, wherein at least one search area among the plurality of search areas includes samples of the current picture located outside the current CTU, and wherein at least one search area among the plurality of search areas does not include samples of the current picture located outside the current CTU; selecting, for each corresponding decoding block and from within the corresponding search area for the corresponding decoding block, a corresponding predictor block among a plurality of predictor blocks; and reconstructing samples of each corresponding decoding block based on samples included in the corresponding predictor block among the plurality of predictor blocks.

[0007] As another example, a device for decoding video data includes: a memory configured to store video data; and one or more processors implemented in circuits and configured to: determine, for each corresponding decoding block in a plurality of decoding blocks of a current decoding tree unit (CTU) of the video data in a current picture of the video data, a corresponding search area among a plurality of corresponding search areas, wherein the search areas among the plurality of search areas are different, wherein at least one search area among the plurality of search areas includes samples of the current picture located outside the current CTU, and wherein at least one search area among the plurality of search areas does not include samples of the current picture located outside the current CTU; for each corresponding decoding block, and from within the corresponding search area for the corresponding decoding block, select a corresponding predictor block among a plurality of predictor blocks; and reconstruct samples of each corresponding decoding block based on samples included in a corresponding predictor block among the plurality of predictor blocks.

[0008] As another example, a video decoder includes: a component for determining, for each corresponding decoding block in a plurality of decoding blocks of a current decoding tree unit (CTU) of the video data in a current picture of the video data, a corresponding search area among a plurality of corresponding search areas, wherein the search areas among the plurality of search areas are different, wherein at least one search area among the plurality of search areas includes samples of the current picture located outside the current CTU, and wherein at least one search area among the plurality of search areas does not include samples of the current picture located outside the current CTU; a component for selecting, for each corresponding decoding block and from within the corresponding search area for the corresponding decoding block, a corresponding predictor block among a plurality of predictor blocks; and a component for reconstructing samples of each corresponding decoding block based on samples included in a corresponding predictor block among the plurality of predictor blocks.

[0009] As another example, a computer-readable storage medium storing instructions that, when executed, cause one or more processors to: determine, for each corresponding decoding block in a plurality of decoding blocks of a current decoding tree unit (CTU) of video data in a current picture of video data, a corresponding search area among a plurality of corresponding search areas, wherein the search areas among the plurality of search areas are different, wherein at least one search area among the plurality of search areas includes samples of the current picture located outside the current CTU, and wherein at least one search area among the plurality of search areas does not include samples of the current picture located outside the current CTU; for each corresponding decoding block, and from within the corresponding search area for the corresponding decoding block, select a corresponding predictor block among a plurality of predictor blocks; and reconstruct samples of each corresponding decoding block based on samples included in a corresponding predictor block among the plurality of predictor blocks.

[0010] 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

[0011] Figure 1 is a block diagram illustrating an example video encoding and decoding system that may perform the techniques of this disclosure.

[0012] Figure 2 is a diagram illustrating an example of an intra-block copy process in accordance with one or more techniques of this disclosure.

[0013] Figure 3A and 3B is a conceptual diagram illustrating an example quadtree binary tree (QTBT) structure and a corresponding coding tree unit (CTU).

[0014] Figure 4 is a block diagram illustrating an example video encoder that may perform the techniques of this disclosure.

[0015] Figure 5 is a block diagram illustrating an example video decoder that may perform the techniques of this disclosure.

[0016] Figure 6 is a conceptual diagram illustrating a CTU using pipeline coding in accordance with one or more techniques of this disclosure.

[0017] Figure 7 is a conceptual diagram illustrating an example search area for CPR, in accordance with one or more techniques of this disclosure.

[0018] Figure 8 is a conceptual diagram illustrating an example search area for CPR, in accordance with one or more techniques of this disclosure.

[0019] Figures 9A-9C is a conceptual diagram illustrating example search areas for performing CPR in various scan orders, in accordance with one or more techniques of this disclosure.

[0020] Fig.10 is a conceptual diagram illustrating an example search area for CPR, in accordance with one or more techniques of this disclosure.

[0021] Fig.11 is a conceptual diagram illustrating an example search area for CPR, in accordance with one or more techniques of this disclosure.

[0022] Figures 12A-12D is a conceptual diagram illustrating an example search area for performing CPR for various coding blocks of a CTU, in accordance with one or more techniques of this disclosure.

[0023] Fig.13 is a flow chart illustrating an example method for encoding a current block.

[0024] Fig.14 is a flow chart illustrating an example method for decoding a current block.

[0025] Fig.15 is a flow chart illustrating an example method for predicting a block of video data in a current picture using a hybrid search area, according to techniques of this disclosure. DETAILED DESCRIPTION

[0026] Video coding standards include ITU-T H.261, ISO / IEC MPEG-1 Visual, ITU-T H.262 or ISO / IEC MPEG-2 Visual, ITU-T H.263, ISO / IEC MPEG-4 Visual, and ITU-T H.264 (also known as ISO / IEC MPEG-4 AVC) including its scalable video coding (SVC) and multi-view video coding (MVC) extensions.

[0027] High Efficiency Video Coding (HEVC) was finalized in April 2013 by the Joint Collaboration Team on Video Coding (JCT-VC) of the ITU-T Video Coding Experts Group (VCEG) and the ISO / IEC Moving Picture Experts Group (MPEG).

[0028] The Joint Video Experts Group (JVET), a collaborative group formed by MPEG and VCEG of ITU-T Study Group 16, is currently working on a new video coding standard to be called Versatile Video Coding (VVC). The main goal of VVC is to provide significant improvements in compression performance over the existing HEVC standard, helping to deploy higher quality video services and emerging applications such as 360° immersive multimedia and high dynamic range (HDR) video. The development of the VVC standard is expected to be completed in 2020.

[0029] Current Picture Reference (CPR) or Intra Block Copy (IBC) (described in "Intra Block Copy in HEVC Screen Content Coding Extensions" by X. Xu, S. Liu, T. Chuang, Y. Huang, S. Lei, K. Rapaka, C. Pang, V. Seregin, Y. Wang, and M. Karczewicz, IEEE J. Emerg. Sel. Topics in Circuits Systems, Vol. 6, No. 4, 2016, pp. 409-419) has been proposed during the standardization of the HEVC SCC extension (see, e.g., High Efficiency Video Coding (HEVC), Rec. ITU-T H.265 and ISO / IEC 23008-2, December 2016). IBC has been shown to be effective in coding screen content video material. This approach was previously proposed in JVET-J0029 and JVET-J0050 to meet the need for efficient screen content decoding. At the 11th JVET meeting, the CPR mode (Xiaozhong Xu, Xiang Li, and Shan Liu, "CE8-2.2: Current picture referencing using reference index signaling", JVET-K0076, ljubljana, SL, July 2018 (hereinafter referred to as "JVET-K0076")) was adopted into the benchmark set (BMS) software of VVC for further evaluation.

[0030] The current picture reference (CPR) mode described in JVET-K0076 has been adopted into the BMS software. In CPR mode, the video decoder predicts the intra-block copy (IBC) block in the current picture from the decoded predictor block of the current picture (before loop filtering, such as one or both of adaptive loop filter (ALF) and sample adaptive offset (SAO)). For example, to predict the current block using the CPR mode, the video encoder can select a predictor block from the reference region. The video encoder can select the predictor block as the block in the reference region that most closely matches the samples of the current block (for example, to reduce the size of the residual data). The video encoder can encode a vector (such as a block vector, motion vector, etc.) representing the displacement between the current block and the selected predictor block, and residual data representing the difference between the samples of the predictor block and the samples of the current block. The video decoder can decode the current block using a reciprocal process. For example, the video decoder can decode the vector and the residual data, select the predictor block based on the vector, and reconstruct the samples of the current block based on the samples of the predictor block and the residual data.

[0031] In the current CPR mode, the reference area (i.e., the area of ​​the current picture from which the predictor block can be selected) can be limited to the reconstructed samples of the current coding tree unit (CTU) that includes the block being predicted. Thus, in the current CPR mode, the video decoder can use the predictor block located in the specific CTU to predict the decoded block of the specific CTU. Limiting the reference area to the current CTU can reduce the storage required to predict the block using the CPR mode. For example, limiting the reference area to the current CTU can cause the video decoder to access / store only the samples of the current CTU when decoding the current CTU. However, this limitation may reduce the performance of CPR decoding compared to having a larger reference area. Specifically, limiting the reference area to the current CTU may reduce the probability of utilizing the predictor block with samples matching the current block, which may result in an increase in the size of the residual data. The increase in the size of the residual data may undesirably reduce the decoding efficiency (e.g., more bits are required to represent the video data).

[0032] According to one or more techniques of the present disclosure, when decoding a block of video data using a CPR mode, a video decoder (e.g., video encoder 200 and / or video decoder 300) can utilize a hybrid search area. For example, the video decoder can utilize a different search area for each decoded block of a CTU of a current picture. The search area can be considered to be hybrid because the search area of ​​at least one decoded block includes samples of the current picture that are located outside the current CTU, and the search area of ​​at least one decoded block does not include samples of the current picture that are located outside the current CTU. By utilizing a hybrid search area, the video decoder can balance storage and decoding efficiency for performing CPR.

[0033] Figure 1 1 is a block diagram illustrating an example video encoding and decoding system 100 that can perform the techniques of the present disclosure. The techniques of the present disclosure generally relate to decoding (encoding and / or decoding) video data. Generally, video data includes any data used to process video. Therefore, video data can include original unencoded video, encoded video, decoded (e.g., reconstructed) video, and video metadata such as signaling data.

[0034] like Figure 1 As 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 video data to destination device 116 via computer-readable medium 110. Source device 102 and destination device 116 may include any of a variety of devices, including desktop computers, notebook (i.e., laptop) computers, tablet computers, set-top boxes, telephone handsets such as smartphones, televisions, cameras, display devices, digital media players, video game consoles, video streaming devices, etc. In some cases, source device 102 and destination device 116 may be equipped for wireless communication and may therefore be referred to as wireless communication devices.

[0035] exist Figure 1 In the example of, source device 102 comprises video source 104, memory 106, video encoder 200 and output interface 108. Destination device 116 comprises 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 the technology of hybrid search area for CPR. Therefore, source device 102 represents an example of video encoding device, and destination device 116 represents an example of video decoding device. In other examples, source device and destination device may include other components or arrangements. For example, source device 102 may receive video data from an external video source (such as an external camera). Similarly, destination device 116 may interface with an external display device instead of including an integrated display device.

[0036] Figure 1The system 100 shown is only an example. In general, any digital video encoding and / or decoding device can perform the technology of hybrid search area for CPR. The source device 102 and the destination device 116 are only examples of such decoding devices, wherein the source device 102 generates decoded video data for transmission to the destination device 116. The present disclosure refers to a "decoding" device as a device that performs decoding (encoding and / or decoding) of data. Therefore, the video encoder 200 and the video decoder 300 represent examples of decoding devices (specifically video encoders and video decoders), respectively. In some examples, the source device 102 and the destination device 116 can operate in a substantially symmetrical manner, so that each of the source device 102 and the destination device 116 includes a video encoding and decoding component. Therefore, the system 100 can support one-way or two-way video transmission between the source device 102 and the destination device 116, such as for video streaming, video playback, video broadcasting or video telephony.

[0037] Typically, video source 104 represents a source of video data (i.e., original, unencoded video data), and provides a continuous sequence of pictures (also referred to as "frames") of video data to video encoder 200, which encodes the data of the pictures. Video source 104 of source device 102 may include a video capture device such as a video camera, a video archive containing previously captured original video, and / or a video feed interface receiving video from a video content provider. As a further alternative, video source 104 may generate computer graphics-based data as source video, or a combination of live video, archived video, and computer-generated video. In each case, video encoder 200 encodes captured, pre-captured, or computer-generated video data. Video encoder 200 may rearrange pictures from a receiving order (sometimes referred to as a "display order") into a decoding order for decoding. Video encoder 200 may generate a bitstream comprising encoded video data. Source device 102 may then output the encoded video data onto computer-readable medium 110 via output interface 108 for receipt and / or retrieval by, for example, input interface 122 of destination device 116 .

[0038] The memory 106 of the source device 102 and the memory 120 of the destination device 116 represent general purpose memory. In some examples, the memories 106, 120 can store original video data, such as original video from the video source 104 and original decoded video data from the video decoder 300. Additionally or alternatively, the memories 106, 120 can store software instructions that can be executed by, for example, the video encoder 200 and the video decoder 300, respectively. Although in this example, the memory 106 and the memory 120 are shown as being separate from the video encoder 200 and the video decoder 300, it should be understood that the video encoder 200 and the video decoder 300 can also include internal memory for functionally similar or equivalent purposes. In addition, the memories 106, 120 can store, for example, encoded video data output from the video encoder 200 and input to the video decoder 300. In some examples, portions of the memories 106, 120 can be allocated as one or more video buffers, for example, to store original decoded and / or encoded video data.

[0039] The computer-readable medium 110 may 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 for enabling the source device 102 to directly transmit the encoded video data to the destination device 116 in real time, for example, via a radio frequency network or a computer-based network. According to a communication standard such as a wireless communication protocol, the output interface 108 may modulate a transmission signal including the encoded video data, and the input interface 122 may demodulate the received transmission signal. The communication medium may include any wireless or wired communication medium, such as a radio frequency (RF) spectrum or one or more physical transmission lines. The communication medium may form part of a packet-based network, such as a local area network, a wide area network, or a global network such as the Internet. The communication medium may include a router, a switch, a base station, or any other device that may be useful for facilitating communication from the source device 102 to the destination device 116.

[0040] 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 for storing encoded video data, 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.

[0041] 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 generated by source device 102. Destination device 116 may access the stored video data from file server 114 via streaming or downloading. File server 114 may be any type of server device capable of storing the encoded video data and sending the encoded video data to destination device 116. File server 114 may represent a network server (e.g., for a website), a file transfer protocol (FTP) server, a content delivery network device, or a network attached storage (NAS) device. Destination device 116 may access the encoded video data from file server 114 via 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.) suitable for accessing the encoded video data stored on file server 114, or a combination of both. File server 114 and input interface 122 may be configured to operate according to a streaming protocol, a downloading transmission protocol, or a combination thereof.

[0042] Output interface 108 and 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 a variety of IEEE 802.11 standards, or other physical components. In examples where output interface 108 and input interface 122 include wireless components, output interface 108 and 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 output interface 108 includes a wireless transmitter, output interface 108 and 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 TM ),Bluetooth TM Standards, etc.) for transmitting data (such as encoded video data). In some examples, source device 102 and / or destination device 116 may include respective system-on-chip (SoC) devices. For example, source device 102 may include an SoC device that performs functions considered as video encoder 200 and / or output interface 108, and destination device 116 may include an SoC device that performs functions considered as video decoder 300 and / or input interface 122.

[0043] 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.

[0044] The input interface 122 of the destination device 116 receives the 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 defined by the video encoder 200 and also used by the video decoder 300, such as syntax elements having values ​​describing 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 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 cathode ray tube (CRT), a liquid crystal display (LCD), a plasma display, an organic light emitting diode (OLED) display, or another type of display device.

[0045] Although in Figure 1 200 and 300 may each be integrated with an audio encoder and / or an audio decoder and may include appropriate MUX-DEMUX units or other hardware and / or software to handle multiplexed streams of both audio and video included in a common data stream. If applicable, the MUX-DEMUX units may conform to the ITU H.223 multiplexer protocol, or other protocols such as the User Datagram Protocol (UDP).

[0046] The video encoder 200 and the video decoder 300 can each be implemented as any of a variety of suitable encoder and / or decoder circuit systems, 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 these techniques are partially implemented in software, the device can store instructions for the software in a suitable non-transitory computer-readable medium and use one or more processors to execute these instructions in hardware to perform the techniques 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 a corresponding device. A 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).

[0047] The video encoder 200 and the video decoder 300 may operate according to a video coding standard, such as ITU-T H.265, also known as High Efficiency Video Coding (HEVC), or an extension thereof, such as multi-view and / or scalable video coding extensions. Alternatively, the video encoder 200 and the video decoder 300 may operate according to other proprietary standards or industry standards, such as the Joint Exploration Test Model (JEM) or ITU-T H.266, also known as Versatile Video Coding (VVC). The latest draft of the VVC standard is described in "Versatile Video Coding (Draft 6)" of the 11th meeting of the Joint Video Experts Group (JVET) of ITU-T SG16WP 3 and ISO / IEC JTC 1 / SC 29 / WG 11 by Bross et al.: The meeting was held in ljubljana, SI, July 10-18, 2018, JVET-K1001-v6 (hereinafter referred to as "VVC Draft 2"). However, the techniques of this disclosure are not limited to any particular coding standard.

[0048] Typically, the video encoder 200 and the 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., data that is encoded, decoded, or otherwise used in an encoding and / or decoding process). For example, a block may include a two-dimensional matrix of samples of luminance and / or chrominance data. Typically, the video encoder 200 and the video decoder 300 can decode video data represented in a YUV (e.g., Y, Cb, Cr) format. That is, the video encoder 200 and the video decoder 300 can decode luminance components and chrominance components instead of decoding red, green, and blue (RGB) data of the picture samples, where the chrominance components may include red-toned and blue-toned chrominance components. In some examples, the video encoder 200 converts the received RGB format data into a YUV representation before encoding, and the video decoder 300 converts the YUV representation into an RGB format. Optionally, a pre-processing unit and a post-processing unit (not shown) can perform these conversions.

[0049] The present disclosure may generally refer to the decoding (e.g., encoding and decoding) of a picture to include the process of encoding or decoding the data of a picture. Similarly, the present disclosure may refer to the decoding of a block of a picture to include the process of encoding or decoding the data of the block, such as prediction and / or residual decoding. The encoded video bitstream generally includes a series of values ​​of syntax elements that represent decoding decisions (e.g., decoding modes) and partitioning of the picture into blocks. Therefore, references to the decoding of a picture or a block should generally be understood as decoding the values ​​of the syntax elements that form the picture or block.

[0050] HEVC defines various blocks, including coding units (CUs), prediction units (PUs), and transform units (TUs). According to HEVC, a video decoder (such as 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 PU and TU. For example, in HEVC, the residual quadtree (RQT) represents the partitioning of the TU. In HEVC, PU represents inter-frame prediction data, and TU represents residual data. The intra-predicted CU includes intra-frame prediction information, such as an intra-frame mode indication.

[0051] As another example, the video encoder 200 and the video decoder 300 may be configured to operate according to JEM or VVC. According to JEM or VVC, a video decoder (e.g., video encoder 200) partitions a picture into a plurality of coding tree units (CTUs). The video encoder 200 may partition the CTUs according to a tree structure such as a quadtree-binary tree (QTBT) structure or a multi-type tree (MTT) structure. The QTBT structure eliminates the concept of multiple partition types, such as the separation between CU, PU, ​​and TU of HEVC. The QTBT structure includes two levels: a first level partitioned according to a quadtree split and a second level partitioned according to a binary tree split. The root node of the QTBT structure corresponds to the CTU. The leaf nodes of the binary tree correspond to coding units (CUs).

[0052] In the MTT partitioning structure, blocks can be partitioned using quadtree (QT) partitioning, binary tree (BT) partitioning, and one or more types of triple tree (TT) (also called ternary tree (TT)) partitioning. Triple tree or ternary tree partitioning is a partitioning that splits a block into three sub-blocks. In some examples, triple tree or ternary tree partitioning divides a block into three sub-blocks without dividing the original block through the center. The partitioning types in MTT (such as QT, BT, and TT) can be symmetric or asymmetric.

[0053] 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 corresponding chroma components).

[0054] The video encoder 200 and the video decoder 300 may be configured to use quadtree splitting per HEVC, QTBT splitting, MTT splitting, or other splitting structures. For purposes of explanation, the description of the disclosed techniques is presented for QTBT splitting. However, it should be understood that the disclosed techniques may also be applied to video decoders configured to use quadtree splitting or other types of splitting.

[0055] Blocks (e.g., CTUs or CUs) may be grouped in a picture in various ways. As an example, a brick may refer to a rectangular region of a CTU row within a particular tile in a picture. A slice may be a rectangular region of a CTU within a particular slice column and a particular slice row in a picture. A slice column refers to a rectangular region of a CTU having a height equal to the picture height and a width specified by a syntax element (e.g., such as in a picture parameter set). A slice row refers to a rectangular region of a CTU having a height specified by a syntax element (e.g., such as in a picture parameter set) and a width equal to the picture width.

[0056] In some examples, a slice may be partitioned into multiple bricks, each of which may include one or more CTU rows within the slice. A slice 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 slice cannot be referred to as a slice.

[0057] The 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 contained exclusively in a single network abstraction layer (NAL) unit. In some examples, a slice includes a continuous sequence of multiple complete slices or only complete tiles of a slice.

[0058] The present disclosure may use "NxN" and "N by N" interchangeably to refer to the sample dimensions of a block (such as a CU or other video block) in the vertical and horizontal dimensions, for example, 16×16 samples or 16 by 16 samples. Generally speaking, a 16x16 CU has 16 samples in the vertical direction (y=16) and 16 samples in the horizontal direction (x=16). Similarly, an NxN CU 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 can be arranged in rows and columns. In addition, a CU does not necessarily need to have the same number of samples in the horizontal and vertical directions. For example, a CU may include NxM samples, where M is not necessarily equal to N.

[0059] The video encoder 200 encodes the video data of the CU representing the prediction and / or residual information and other information. The prediction information indicates how to predict the CU in order to form a predictor block for the CU. The residual information generally represents the sample-by-sample difference between the CU samples before encoding and the predictor block.

[0060] In order to predict a CU, the video encoder 200 may typically form a predictor block for the CU by 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. In order to perform inter-frame prediction, the video encoder 200 may use one or more motion vectors to generate a predictor block. The video encoder 200 may typically perform a motion search to identify a reference block that closely matches the CU, for example, relative to 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.

[0061] Some examples of JEM and VVC also provide an affine motion compensation mode, which can be considered an inter-prediction mode. In the affine motion compensation mode, the video encoder 200 can determine two or more motion vectors representing non-translational motion, such as enlargement or reduction, rotation, perspective motion, or other irregular motion types.

[0062] In order to perform intra prediction, the video encoder 200 can select an intra prediction mode to generate a predictor block. Some examples of JEM and VVC provide 67 intra prediction modes, including modes of various directions, as well as planar modes and DC modes. Typically, the video encoder 200 selects an intra prediction mode that describes the neighboring samples to the current block (e.g., a block of a CU), and predicts the samples of the current block based on the neighboring samples. Assuming that the video encoder 200 decodes the CTU and CU in a raster scan order (from left to right, from top to bottom), such samples can typically be above, above left, or to the left of the current block in the same picture as the current block.

[0063] The video encoder 200 encodes data representing the prediction mode of 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 is used and motion information of the corresponding mode. For example, for unidirectional or bidirectional inter-frame prediction, 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.

[0064] After prediction (such as intra-frame prediction or inter-frame prediction of a block), the video encoder 200 can 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 predictor block formed using a corresponding prediction mode for the block. The video encoder 200 can apply one or more transforms to the residual block to generate transform data in a transform domain rather than a sample domain. For example, the video encoder 200 can 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 can apply a secondary transform after a primary transform, such as a mode-dependent non-separable secondary transform (MDNSST), a signal-dependent transform, a Karhunen-Loeve transform (KLT), etc. The video encoder 200 generates transform coefficients after applying one or more transforms.

[0065] As described above, after any transform used to produce transform coefficients, the video encoder 200 can perform quantization of the transform coefficients. Quantization generally refers to the process of quantizing the transform coefficients to minimize the amount of data used to represent the transform coefficients, thereby providing further compression. By performing the quantization process, the video encoder 200 can reduce the bit depth associated with some or all transform coefficients. For example, the video encoder 200 can 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 can perform a bitwise right shift on the value to be quantized.

[0066] After quantization, the video encoder 200 can scan the transform coefficients to generate a one-dimensional vector from a two-dimensional matrix including the quantized transform coefficients. The scan can be designed to place coefficients of higher energy (and therefore lower frequency) in front of the vector and transform coefficients of lower energy (and therefore higher frequency) in the back of the vector. In some examples, the video encoder 200 can scan the quantized transform coefficients using a predefined scan order to generate a serialized vector, and then entropy encode the quantized transform coefficients of the vector. In other examples, the video encoder 200 can perform adaptive scanning. After scanning the quantized transform coefficients to form a one-dimensional vector, the video encoder 200 can entropy encode the one-dimensional vector, for example, according to context adaptive binary arithmetic coding (CABAC). The video encoder 200 can also entropy encode the values ​​of the syntax elements describing the metadata associated with the encoded video data for use by the video decoder 300 when decoding the video data.

[0067] To perform CABAC, the video encoder 200 may assign context in 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.

[0068] The video encoder 200 may also generate syntax data (such as block-based syntax data, picture-based syntax data, and sequence-based syntax data) to the video decoder 300, for example, in a picture header, a block header, a slice header, or other syntax data such as a sequence parameter set (SPS), a picture parameter set (PPS), or a video parameter set (VPS). The video decoder 300 may also decode such syntax data to determine how to decode the corresponding video data.

[0069] In this way, the video encoder 200 can generate a bitstream including encoded video data, for example, a syntax element describing the partitioning of a picture into blocks (eg, CUs) and prediction and / or residual information of the blocks. Finally, the video decoder 300 can receive the bitstream and decode the encoded video data.

[0070] In general, the video decoder 300 performs a process that is the reverse of 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 the syntax elements of the bitstream in a manner substantially similar to but reverse to the CABAC encoding process of the video encoder 200. The syntax elements may define information for splitting a picture into CTUs, and partition 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 video data block (e.g., a CU).

[0071] 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 the associated prediction information (e.g., motion information for inter-frame prediction) to form a predictor block for the block. The video decoder 300 may then combine the predictor 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 performing deblocking, to reduce visual artifacts along block boundaries.

[0072] Figure 2 is a diagram illustrating an example of a current picture reference (CPR) decoding process according to one or more techniques of this disclosure. According to an exemplary CPR process, video encoder 200 may select a predictor video block, for example, from a set of previously decoded and reconstructed blocks of video data located in a search area. Figure 1In the example of , search area 8 includes a set of previously decoded and reconstructed video blocks. The blocks in search area 8 may represent blocks that have been decoded and reconstructed by video decoder 300 and stored in decoded picture buffer 314, or blocks that have been decoded and reconstructed in a reconstruction loop of video encoder 200 and stored in decoded picture buffer 218. Current block 2 represents a current block of video data to be decoded. Predictor block 4 represents a reconstructed video block in the same picture as current block 2, which is used for BC intra prediction of current block 2.

[0073] In the example CPR process, the video encoder 200 may determine and encode a motion vector 6 indicating the position of the predictor block 4 relative to the current block 2 and a residual signal. Figure 1 As shown, motion vector 6 may indicate the position of the upper left corner of predictor block 4 relative to the upper left corner of current block 2. Motion vector 6 may also be referred to as an offset vector, a displacement vector, or a block vector (BV). Video decoder 300 may utilize the encoded information to decode the current block.

[0074] As described above, in the current CPR mode, the reference area (e.g., search area 8) can be limited to the reconstructed samples of the current coding tree unit (CTU) that includes the block being predicted (e.g., the CTU that includes the current block 2). This limitation may be advantageous because it reduces the amount of memory required to perform CPR. However, as described above, this limitation may reduce the decoding efficiency of CPR.

[0075] According to one or more techniques of the present disclosure, when a block of video data is decoded using a CPR mode, a video decoder (e.g., video encoder 200 and / or video decoder 300) may utilize a hybrid search area. For example, the video decoder may determine a corresponding search area in a plurality of corresponding search areas for each corresponding decoding block in a plurality of decoding blocks of a current decoding tree unit (CTU) of the video data in a current picture of the video data. The search areas in the plurality of search areas may all be different. For example, the search area for any given decoding block of the CTU may be different from the search area for any other decoding block of the CTU. The search area may be considered hybrid because the search area for at least one decoding block includes samples of the current picture located outside the current CTU, and the search area for at least one decoding block does not include samples of the current picture located outside the current CTU. By utilizing a hybrid search area, the video decoder may balance storage and decoding efficiency for performing CPR.

[0076] The present disclosure may generally refer to "signaling" certain information, such as syntax elements. The term "signaling" may generally refer to the communication of values ​​of syntax elements and / or other data used to decode encoded video data. That is, the video encoder 200 may signal the values ​​of syntax elements in a bitstream. Generally, signaling refers to generating values ​​in a bitstream. As described above, the source device 102 may transmit the bitstream to the destination device 116 in substantially real time or in non-real time (such as may occur when the syntax elements are stored to the storage device 112 for later retrieval by the destination device 116).

[0077] Figure 3A and 3B 1 is a conceptual diagram illustrating an example quadtree binary tree (QTBT) structure 130 and a corresponding coding tree unit (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 horizontal splitting and 1 indicates vertical splitting. For quadtree splitting, since the quadtree node splits a block horizontally and vertically into 4 sub-blocks of equal size, there is no need to indicate the split type. Accordingly, the video encoder 200 can encode syntax elements (such as split information) for the region tree level (i.e., solid line) of the QTBT structure 130 and syntax elements (such as split information) for the prediction tree level (i.e., dashed line) of the QTBT structure 130, and the video decoder 300 can decode the above syntax elements. The video encoder 200 may encode video data (such as prediction and transform data) for a CU represented by a terminal leaf node of the QTBT structure 130 , and the video decoder 300 may decode the above video data.

[0078] generally, Figure 3B The CTU 132 of the first level and the second level QTBT structure 130 may be associated with parameters that define the size of the blocks corresponding to the nodes of the first level and the second level. These parameters may include a CTU size (indicating the size of the CTU 132 in the sample), 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).

[0079] The root node of the QTBT structure corresponding to the CTU may have four child nodes at the first level of the QTBT structure, and each child node may be segmented according to the quadtree segmentation. That is, the node at the first level is a leaf node (without child nodes) or has four child nodes. The example of the QTBT structure 130 represents such a node, which includes a parent node and a child node with a solid line branch. If the node at the first level is not larger than the maximum allowed binary tree root node size (MaxBTSize), the node can be further segmented by the respective binary trees. The binary tree splitting of a node can be iterated until the node generated by 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 a node as having a dotted line branch. The binary tree leaf node is called a decoding unit (CU), which is used for prediction (e.g., intra-picture or inter-picture prediction) and transformation without any further segmentation. As described above, a CU may also be referred to as a "video block", "coding block" or "block".

[0080] In one example of a QTBT partitioning structure, the CTU size is set to 128×128 (luminance sample and two corresponding 64×64 chroma samples), MinQTSize is set to 16×16, MaxBTSize is set to 64×64, 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 a quadtree leaf node. The quadtree leaf node can have a size from 16×16 (ie, MinQTSize) to 128×128 (ie, CTU size). If the leaf quadtree node is 128×128, since its size exceeds MaxBTSize (64×64 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 of 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), this means that no further horizontal splitting is allowed. Similarly, a binary tree node with a height equal to MinBTSize means that no further vertical splitting is allowed for 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.

[0081] In some examples, the video coder may perform block compensation with integer block compensation on luma components coded with CPR. In this way, the video coder may avoid performing interpolation on luma components. In some instances, the video coder may perform block compensation on chroma components using sub-pixel block compensation. In this way, the video coder may perform interpolation on chroma components.

[0082] Figure 4 is a block diagram illustrating an example video encoder 200 that may perform the techniques of this disclosure. Figure 4 The above description is provided for the purpose of explanation and should not be considered as limiting the techniques widely exemplified and described in this disclosure. For the purpose of illustration, this disclosure describes the video encoder 200 in the context of video coding standards such as the HEVC video coding standard under development and the 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.

[0083] exist Figure 4 In the example of , 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 can be implemented in one or more processors or processing circuits. For example, the units of the video encoder 200 can be implemented as one or more circuits or logic elements as part of a hardware circuit, or as part of a processor ASIC of an FPGA. In addition, the video encoder 200 may include additional or alternative processors or processing circuits to perform these and other functions.

[0084] 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 video data memory 230. DPB 218 can be used as a reference picture memory, which stores reference video data for use by video encoder 200 when predicting subsequent video data. Video data memory 230 and DPB 218 can be formed by any of a variety of storage devices, such as dynamic random access memory (DRAM) including synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of storage devices. Video data memory 230 and DPB 218 can be provided by the same storage device or a separate storage device. In various examples, video data memory 230 can be placed on the chip with other components of video encoder 200, as shown, or placed off-chip relative to those components.

[0085] In the present disclosure, references to the video data memory 230 should not be interpreted as limited to memory internal to the video encoder 200 (unless specifically stated otherwise) or memory external to the video encoder 200 (unless specifically stated otherwise). Rather, references to the video data memory 230 should be understood as a reference memory for storing encoded video data (e.g., video data of a current block to be encoded) received by the video encoder 200. Figure 1 The memory 106 may also provide temporary storage for outputs from various units of the video encoder 200 .

[0086] Picture shows Figure 4 The various units are used 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 preset operations that can be performed. Programmable circuits refer to circuits that can be programmed to perform various tasks and provide flexible functions in the operations that can be performed. For example, a programmable circuit can execute software or firmware, and the software or firmware 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 (for example, to receive parameters or output parameters), but the type of operation performed by the fixed-function circuit is generally immutable. In some examples, one or more units may be different circuit blocks (fixed function or programmable), and in some examples, one or more units may be integrated circuits.

[0087] 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 instructions (eg, object code) for software received and executed by the video encoder 200, or another memory (not shown) within the video encoder 200 may store such instructions.

[0088] The video data memory 230 is configured to store received video data. The video encoder 200 may retrieve pictures of 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 may be original video data to be encoded.

[0089] 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 for performing video prediction according to other prediction modes. As an 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.

[0090] The mode selection unit 202 typically coordinates multiple encoding passes to test combinations of encoding parameters and the resulting rate-distortion values ​​for these combinations. The encoding parameters may include the partitioning of CTUs into CUs, the prediction mode of the CUs, the transform type of the residual data of the CUs, the quantization parameter of the residual data of the CUs, 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.

[0091] The video encoder 200 may partition the picture retrieved from the video data memory 230 into a series of CTUs and encapsulate one or more CTUs in 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 form one or more CUs by partitioning the CTUs according to the tree structure. Such CUs may also be generally referred to as "video blocks" or "blocks".

[0092] Typically, the mode selection unit 202 also controls its components (e.g., the motion estimation unit 222, the motion compensation unit 224, and the intra prediction unit 226) to generate a predictor block for the current block (e.g., the overlapping portion of the current CU or PU and TU in HEVC). In order to inter-predict the current block, the motion estimation unit 222 can 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 the DPB 218). Specifically, the motion estimation unit 222 can calculate values ​​indicating how similar the potential reference blocks are to the current block based on, for example, the sum of absolute differences (SAD), the sum of squared differences (SSD), the mean absolute difference (MAD), the mean squared difference (MSD), etc. The motion estimation unit 222 can typically perform these calculations using the sample-by-sample differences between the current block and the reference block under consideration. The motion estimation unit 222 can identify the reference block having the lowest value generated from these calculations, which indicates the reference block that most closely matches the current block.

[0093] The 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 a current block in a current picture. The motion estimation unit 222 may then provide the motion vectors to the motion compensation unit 224. For example, for unidirectional inter prediction, the motion estimation unit 222 may provide a single motion vector, while for bidirectional inter prediction, the motion estimation unit 222 may provide two motion vectors. The motion compensation unit 224 may then use the motion vectors to generate a predictor block. For example, the 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, the motion compensation unit 224 may interpolate the predictor block according to one or more interpolation filters. In addition, for bidirectional inter prediction, the motion compensation unit 224 may retrieve data for two reference blocks identified by the corresponding motion vectors and combine the retrieved data, for example, by sample-by-sample averaging or weighted averaging.

[0094] As another example, for intra prediction or intra prediction decoding, the intra prediction unit 226 may generate a predictor block based on samples adjacent to the current block. For example, for directional mode, the intra prediction unit 226 may generally mathematically combine the values ​​of the adjacent samples and fill these calculated values ​​along a defined direction on the current block to generate the predictor block. As another example, for DC mode, the intra prediction unit 226 may calculate the average value of the adjacent samples of the current block and generate the predictor block to include the average value obtained for each sample of the predictor block.

[0095] The mode selection unit 202 provides the predictor block to the residual generation unit 204. The residual generation unit 204 receives the original uncoded version of the current block from the video data memory 230 and receives the predictor block from the mode selection unit 202. The residual generation unit 204 calculates the sample-by-sample difference between the current block and the predictor block. The resulting sample-by-sample difference defines a residual block for the current block. In some examples, the residual generation unit 204 may also use residual differential pulse coding modulation (RDPCM) to determine the difference between the sample values ​​in the residual block to generate the residual block. In some examples, the residual generation unit 204 may be formed using one or more subtractor circuits that perform binary subtraction.

[0096] In the example where the mode selection 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 described above, the size of the CU may refer to the size of the luma coding block of the CU, and the size of the PU may refer to the size of the luma prediction unit of the PU. Assuming that the size of a particular CU is 2N×2N, the video encoder 200 may support PU sizes of 2N×2N or N×N for intra-frame prediction, and symmetric PU sizes of 2N×2N, 2N×N, N×2N, N×N or the like for inter-frame prediction. The video encoder 20 and the video decoder 30 may also support asymmetric partitioning of PU sizes of 2N×nU, 2N×nD, nL×2N and nR×2N for inter-frame prediction.

[0097] In an example where the mode selection unit does not further split the CU into PUs, each CU may be associated with a luma coding block and a corresponding chroma coding block. As described above, the size of a CU may refer to the size of the luma coding block of the CU. The video encoder 200 and the video decoder 300 may support a CU size of 2N×2N, 2N×N, or N×2N.

[0098] For other video coding techniques, such as intra-block copy mode coding, affine mode coding, and linear model (LM) mode coding as some examples, the mode selection unit 202 generates a predictor block for the current block being encoded via a corresponding unit associated with the coding technique. In some examples, such as palette mode coding, the mode selection unit 202 may not generate a predictor block, but instead generate a syntax element indicating how the block will be reconstructed based on the selected palette. In such a mode, the mode selection unit 202 may provide these syntax elements to the entropy coding unit 220 for encoding.

[0099] As described above, the residual generation unit 204 receives video data for a current block and a corresponding predictor block. Then, the residual generation unit 204 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 predictor block and the current block.

[0100] 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 a 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, for example, 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.

[0101] 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 coefficient block associated with the current block by adjusting the QP value associated with the CU. Quantization may introduce information loss, and therefore, the quantized transform coefficients may have lower precision than the original transform coefficients produced by the transform processing unit 206.

[0102] 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 (although potentially with some degree of distortion) based on the reconstructed residual block and the predictor 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 of the predictor block generated by the mode selection unit 202 to generate a reconstructed block.

[0103] 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 edge of the CU. In some examples, the operations of filter unit 216 may be skipped.

[0104] The video encoder 200 stores the reconstructed blocks in the DPB 218. For example, in an example where the operation of the filter unit 216 is not required, the reconstruction unit 214 can store the reconstructed blocks in the DPB 218. In an example where the operation of the filter unit 216 is required, the filter unit 216 can store the filtered reconstructed blocks in the DPB 218. The motion estimation unit 222 and the motion compensation unit 224 can retrieve a reference picture from the DPB 218, which is formed by the reconstructed (and potentially filtered) blocks, to perform inter-frame prediction on blocks of subsequently encoded pictures. In addition, the intra-frame prediction unit 226 can use the reconstructed blocks in the DPB 218 of the current picture to perform intra-frame prediction on other blocks in the current picture.

[0105] In general, the entropy coding unit 220 may entropy encode syntax elements received from other functional components of the video encoder 200. For example, the entropy coding unit 220 may entropy encode a block of quantized transform coefficients from the quantization unit 208. As another example, the 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 the mode selection unit 202. The entropy coding unit 220 may perform one or more entropy coding operations on syntax elements of another example of video data to generate entropy-encoded data. For example, the 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-Grund coding operation, or another type of entropy coding operation on the data. In some examples, the entropy coding unit 220 may operate in a bypass mode where the syntax elements are not entropy-encoded.

[0106] The video encoder 200 may output a bitstream including syntax elements of entropy coding required to reconstruct a block of a slice or a picture. Specifically, the entropy coding unit 220 may output a bitstream.

[0107] The above operations are described for blocks. Such descriptions should be understood as operations for luma coding blocks and / or chroma coding blocks. As described above, in some examples, the luma coding block and the chroma coding block are the luma and chroma components of the CU. In some examples, the luma coding block and the chroma coding block are the luma and chroma components of the PU.

[0108] In some examples, the operations performed for the luma coding block do not need to be repeated for the chroma coding block. As an example, the operations for identifying the motion vector (MV) and reference picture for the luma coding block do not need to be repeated to identify the MV and reference picture for the chroma block. Instead, the MV of the luma coding block may be scaled to determine the MV of the chroma block, and the reference picture may be the same. As another example, the intra prediction process may be the same for the luma coding block and the chroma coding block.

[0109] The video encoder 200 represents an example of a device configured to encode video data, the device including a memory configured to store the video data and one or more processing units implemented in circuits and configured to: determine, for each corresponding decoding block of a plurality of decoding blocks of a current decoding tree unit (CTU) of the video data in a current picture of the video data, a corresponding search area of ​​a plurality of corresponding search areas, wherein the search areas of the plurality of search areas are all different (i.e., no two search areas contain the same area, although some search areas may overlap), wherein at least one search area of ​​the plurality of search areas is a search area of ​​the plurality of search areas. The method comprises: providing a video bitstream and encoding one or more syntax elements for each corresponding decoding block and encoding one or more syntax elements for each corresponding decoding block in a video bitstream, wherein at least one search area of ​​the plurality of search areas does not include samples of the current picture located outside the current CTU; for each corresponding decoding block, and from within the corresponding search area for the corresponding decoding block, selecting a corresponding predictor block from a plurality of predictor blocks; reconstructing samples of each corresponding decoding block based on samples included in a corresponding predictor block from the plurality of predictor blocks; and encoding one or more syntax elements in a video bitstream and for each corresponding decoding block in the plurality of decoding blocks, the syntax elements representing a value of a corresponding vector identifying the selected predictor block.

[0110] Figure 5 is a block diagram illustrating an example video decoder 300 that may perform the techniques of this disclosure. Figure 5 It is provided for the purpose of explanation and not limitation of the techniques widely exemplified and described in this disclosure. For the purpose of illustration, this disclosure describes a video decoder 300 according to the technical descriptions of JEM, VVC, and HEVC. However, the techniques of this disclosure can be performed by video decoding devices configured for other video decoding standards.

[0111] exist Figure 5In the example of , 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 can be implemented in one or more processors or processing circuits. For example, the units of the video decoder 300 can be implemented as one or more circuits or logic elements as part of a hardware circuit, or as part of a processor ASIC of an FPGA. In addition, the video decoder 300 may include additional or alternative processors or processing circuits to perform these and other functions.

[0112] The prediction processing unit 304 includes a motion compensation unit 316 and an intra prediction unit 318. The prediction processing unit 304 may include additional units for performing predictions 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.

[0113] 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 obtained from computer readable medium 110 ( Figure 1 ) obtains video data stored in CPB memory 320. CPB memory 320 may include a CPB that stores encoded video data (e.g., syntax elements) from an encoded video bitstream. Moreover, CPB memory 320 may store video data other than syntax elements of decoded pictures, such as temporary data representing outputs from various units of video decoder 300. DPB 314 typically stores decoded pictures, and video decoder 300 may output decoded pictures and / or use them as reference video data when decoding subsequent data or pictures of the encoded video bitstream. CPB memory 320 and DPB 314 may be formed by any of a variety of storage devices, such as dynamic random access memory (DRAM) including SDRAM, MRAM, RRAM, or other types of storage devices. CPB memory 320 and DPB 314 may be provided by the same storage device or a separate storage device. In various examples, CPB memory 320 may be placed on-chip with other components of video decoder 300, or off-chip relative to those components.

[0114] 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 store data together with CPB memory 320 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.

[0115] Graphics Figure 5 The various units of the video decoder 300 are provided to 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. Similar to Figure 3, a fixed-function circuit refers to a circuit that provides a specific function and presets the operations that can be performed. A programmable circuit refers to a circuit that can be programmed to perform various tasks and provide flexible functions in the operations that can be performed. For example, a programmable circuit can execute software or firmware, and the software or firmware 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 (for example, to receive parameters or output parameters), but the type of operation performed by the fixed-function circuit is generally immutable. In some examples, one or more units may be different circuit blocks (fixed function or programmable), and in some examples, one or more units may be integrated circuits.

[0116] The video decoder 300 may include an ALU, an 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 decoder 300 is performed by software executed on a programmable circuit, an on-chip or off-chip memory may store instructions (e.g., object code) of the software received and executed by the video decoder 300.

[0117] The entropy decoding unit 302 may receive the encoded video data from the CPB and entropy decode 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.

[0118] Typically, the video decoder 300 reconstructs a picture on a block-by-block basis. 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").

[0119] The entropy decoding unit 302 may entropy decode syntax elements defining quantized transform coefficients of the quantized transform coefficient block and transform information such as a quantization parameter (QP) and / or (one or more) transform mode indications. The inverse quantization unit 306 may use the QP associated with the quantized transform coefficient block to determine a degree of quantization, and likewise, 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 including the transform coefficients.

[0120] 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 transform coefficient block.

[0121] Further, prediction processing unit 304 generates a predictor 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 predictor block. In this case, the prediction information syntax element may indicate a reference picture in DPB 314 from which the reference block is retrieved, 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 predictor block in the same manner as for motion compensation unit 224 ( Figure 4 ) is performed in a manner substantially similar to that described herein.

[0122] 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 predictor block according to the intra-prediction mode indicated by the prediction information syntax element. Again, the intra-prediction unit 318 may generally generate a predictor block in the same manner as for the intra-prediction unit 226 ( Figure 4 The intra prediction process is performed in a manner substantially similar to that described in the foregoing description. The intra prediction unit 318 may retrieve data of neighboring samples of the current block from the DPB 314.

[0123] The reconstruction unit 310 may reconstruct the current block using the predictor block and the residual block. For example, the reconstruction unit 310 may add samples of the residual block to corresponding samples of the predictor block to reconstruct the current block.

[0124] 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.

[0125] The video decoder 300 may store the reconstructed block in the DPB 314. For example, in an example where the operation of the filter unit 312 is not performed, the reconstruction unit 310 may store the reconstructed block in the DPB 314. In an example where the operation of the filter unit 312 is performed, the filter unit 312 may store the filtered reconstructed block in the DPB 314. As described above, the DPB 314 may provide reference information to the prediction processing unit 304, such as samples of the current picture for intra-frame prediction and previously decoded pictures for subsequent motion compensation. In addition, the video decoder 300 may output a decoded picture (e.g., a decoded video) from the DPB for subsequent presentation on a display such as Figure 1 on a display device 118 of the display device.

[0126] In this manner, the video decoder 300 represents an example of a video decoding device, which includes a memory configured to store video data and one or more processing units, which are implemented in circuits and configured to: determine, for each corresponding decoding block in a plurality of decoding blocks of a current decoding tree unit (CTU) of the video data in a current picture of the video data, a corresponding search area in a plurality of corresponding search areas, wherein the search areas in the plurality of search areas are all different, wherein at least one search area in the plurality of search areas includes samples of the current picture located outside the current CTU, and wherein at least one search area in the plurality of search areas does not include samples of the current picture located outside the current CTU; decode, from a video bitstream and for each corresponding decoding block in a plurality of decoding blocks, one or more syntax elements representing a value of a vector identifying a predictor block in the corresponding search area; for each corresponding decoding block and based on the corresponding vector, select a corresponding predictor block in a plurality of predictor blocks; and reconstruct samples of each corresponding decoding block based on the samples included in the corresponding predictor block in the plurality of predictor blocks.

[0127] Figure 6 is a conceptual diagram illustrating a (coding tree unit) CTU using pipeline decoding according to one or more techniques of this disclosure. Figure 6As shown, CTU 600 can be divided into virtual pipeline data units (VPDUs) 602A-602D (collectively referred to as "VPDUs 602"). For example, in the case where CTU 600 includes 128×128 samples, CTU 600 can be divided into multiple VPDUs 602, each of which can include 64×64 samples. In some embodiments of CPR, a video decoder (e.g., video encoder 200 and / or video decoder 300) can utilize a pipeline of decoding units configured to process 64×64 samples.

[0128] As described above, the present disclosure describes a technique in which a video decoder can include samples from outside the current CTU in a search area (e.g., a CPR search area) used when predicting a coded block of the current CTU using the CPR. The present disclosure describes several techniques for extending the CPR search area, each of which can be used independently or in combination with any other technique.

[0129] According to the first technology of the present disclosure, the video decoder may include the A row above the current CTU and the B column to the left of the current CTU in the CPR search area. The available number of rows A and B may depend on the pixels used by other tools such as intra prediction and deblocking filtering. Including these samples does not significantly increase memory requirements because the samples around the CTU may have been used for intra prediction and deblocking filtering.

[0130] According to the second technology of the present disclosure, the video decoder may use different search areas for different decoding blocks in the current CTU. For example, the video decoder may selectively include the A row above the current CTU and the B column to the left of the current CTU in the CPR search area for some decoding blocks but not other decoding blocks (e.g., the search area of ​​the first technology). As an example, the video decoder may selectively include the A row above the current CTU and the B column to the left of the current CTU in the CPR search area for decoding blocks located at the left and / or upper boundaries of the current CTU.

[0131] Figure 7700 is a conceptual diagram showing an example search area for a CPR according to one or more techniques of the present disclosure. As shown, a CTU 700 may be divided into MxN coding blocks 702(0,0)–702(M-1,N-1). As discussed above, a video decoder may use different search areas for different coding blocks in a current CTU. The search area for a particular coding block of a CTU may be determined based on the position of the particular coding block within the CTU. As an example, a video decoder may include samples from A upper rows of an upper adjacent CTU 704 and an upper left adjacent CTU 708 in a search area for a coding block located in the topmost row of CTU 700 (i.e., a coding block in row n=0). As another example, a video decoder may include samples from B left columns of a left adjacent CTU 706 and an upper left adjacent CTU 708 in a search area for a coding block located in the leftmost column of CTU 700 (i.e., a coding block in column m=0). Thus, the search area of ​​the coding block 702 (0, 0) may include A upper rows from the upper adjacent CTU 704 and the upper left adjacent CTU 708 and B left columns from the left adjacent CTU 706 and the upper left adjacent CTU 708.

[0132] Figure 8 is a conceptual diagram illustrating an example search area for CPR according to one or more techniques of this disclosure. Figure 8 As shown, CTU 800 can be divided into four decoding blocks 802A-802D (collectively referred to as "decoding blocks 802"). In some examples, decoding blocks 802 can be referred to as VPDUs. For example, in the case where CTU 800 includes 128×128 samples, CTU 800 can be split into multiple VPDUs 802, each of which can include 64×64 samples.

[0133] The decoding blocks 802 may be referenced based on their relative positions within the CTU 800. As an example, the decoding block 802A may be referred to as an upper left decoding block. As another example, the decoding block 802B may be referred to as an upper right decoding block. As another example, the decoding block 802C may be referred to as a lower left decoding block. As another example, the decoding block 802D may be referred to as a lower right decoding block.

[0134] CTU 800 may be located in a picture of video data along with other CTUs. Other CTUs may be located in regions referenced based on their relative positions relative to CTU 800. As an example, top-neighboring region 804 may include one or more CTUs located above CTU 800. As another example, left-neighboring region 806 may include one or more CTUs located to the left of CTU 800. As another example, top-left-neighboring region 808 may include a CTU located to the top and left of CTU 800.

[0135] As discussed above, the video decoder can utilize hybrid search areas for the coding blocks in the CTU. For example, the video decoder can utilize a different search area for each of the coding blocks 802. The search areas can be considered hybrid because the search area of ​​at least one of the coding blocks 802 includes samples of the current picture that are outside the CTU 800, and the search area of ​​at least one of the coding blocks 802 does not include samples of the current picture that are outside the CTU 800.

[0136] The video decoder may determine a corresponding search area for each decoding block in the decoding block 802. Figure 8 In the example of , the video decoder can determine that the search area for decoding block 802A includes at least some samples located outside CTU 800. For example, the video decoder can include up to N top rows above CTU 800 (e.g., up to N rows from top neighboring area 804), up to M left columns of CTU 800 (e.g., up to M columns from left neighboring area 806), and / or top left neighboring area 808 in the search area for decoding block 802A. Thus, in some examples, the search area for decoding block 802A can include samples from decoding blocks in CTUs located to the left of decoding block 802A of CTU 800.

[0137] The video decoder may determine that the search area for decoding block 802B includes at least some samples located outside CTU 800 and at least some samples located inside CTU 800. For example, the video decoder may include up to N top rows above CTU 800 (e.g., up to N rows from upper neighboring area 804) and / or samples from decoding block 802A in the search area for decoding block 802B.

[0138] The video decoder may determine that the search area for coding block 802C includes at least some samples located outside CTU 800 and at least some samples located inside CTU 800. For example, the video decoder may include up to M left columns of CTU 800 (e.g., up to M columns from left neighboring area 806), samples from coding block 802A, and / or samples from coding block 802B in the search area for coding block 802B.

[0139] The video decoder may determine that the search area for decoding block 802C does not include samples located outside CTU 800. For example, the video decoder may include upper samples from decoding block 802A, samples from decoding block 802B, and / or samples from decoding block 802C in the search area for decoding block 802B. However, the video decoder may not include samples from the left neighboring area 806 in the search area for decoding block 802B.

[0140] In view of the above, in some examples, the video decoder may determine that the corresponding search areas for the upper left decoding block, the upper right decoding block, and the lower left decoding block include samples of the current picture located outside the current CTU. For example, the video decoder may determine that the search area for each of the decoding blocks 802A, 802B, and 802C includes samples located outside the CTU 800. Similarly, the video decoder may determine that the corresponding search areas for the upper left decoding block and the lower left decoding block include samples of the current picture located in the left adjacent CTU of the current CTU. For example, the video decoder may determine that the search area for each of the decoding blocks 802A and 802C includes samples in the CTU located in the left adjacent area 806.

[0141] Additionally, in some examples, the video decoder may determine that the corresponding search area for the bottom right decoding block does not include samples of the current picture that are outside the current CTU. For example, the video decoder may determine that the search area for decoding block 802D does not include samples that are outside CTU 800. Similarly, the video decoder may determine that the corresponding search area for the bottom right decoding block includes the top left decoding block, the top right decoding block, and the bottom left decoding block. For example, the video decoder may determine that the search area for decoding block 802D includes samples from decoding blocks 802A, 802B, and 802C.

[0142] According to the third technology of the present disclosure, the video decoder can decode the current VPDU of the current CTU using a CPR with a search area that includes previously decoded VPDUs within the current CTU and a coded area within the current VPDU. Which VPDUs are considered to be previously decoded VPDUs can be a function of the decoding order.

[0143] Figures 9A-9C is a conceptual diagram illustrating example search areas for performing CPR in various scan orders, in accordance with one or more techniques of this disclosure. Figures 9A-9C Each of the diagrams shows a current CTU 900 divided into MxN VPDUs 902(0,0)-902(M-1,N-1) (collectively referred to as "VPDU 902"). For the purpose of explanation, VPDU 902(1,1) will be used as the current VPDU. As shown in diagrams 902A-902C, VPDU 902(1,1) can be divided into blocks 904A-904D (collectively referred to as "block 904"). Figures 9A-9C In each of , the video decoder may include a shadow VPDU for VPDU 902 in a search area for VPDU 902 (1, 1) (ie, the current VPDU).

[0144] Fig. 9A An example search area for performing CPR in a horizontal raster scan order (e.g., from left to right, from top to bottom) is shown. Fig. 9A As shown, the video decoder may include VPDUs in the VPDU row above the current VPDU and the VPDU to the left of the current VPDU at the same VPDU row in the search area for the current VPDU. In some examples, the video decoder may include blocks within the current VPDU in the search area for other blocks within the current VPDU. For example, the video decoder may include blocks 904A, 904B, and 904C in the search area for block 904D. In some examples, the video decoder may include the VPDU shown as white (unshaded) in VPDU 902 in the search area for blocks of CTU 900, the above VPDU containing samples from a previously processed CTU (e.g., a CTU immediately preceding CTU 900 in decoding order).

[0145] Fig. 9B An example search area for performing CPR in a vertical raster scan order (e.g., from top to bottom, from left to right) is shown. Fig. 9BAs shown, the video decoder may include VPDUs in a VPDU column to the left of the current VPDU and VPDUs above the current VPDU at the same VPDU column in the search area for the current VPDU. In some examples, the video decoder may include blocks within the current VPDU in the search area for other blocks within the current VPDU. For example, the video decoder may include blocks 904A, 904B, and 904C in the search area for block 904D. In some examples, the video decoder may include VPDUs shown as white (unshaded) in VPDU 902 in the search area for blocks of CTU 900, the above VPDUs containing samples from a previously processed CTU (e.g., a CTU immediately preceding CTU 900 in decoding order).

[0146] Fig. 9C An example search area for performing CPR in a zig-zag scan sequence is shown. Fig. 9C As shown, the video decoder may include a VPDU located to the left of the current VPDU in a Z-shaped order in the search area for the current VPDU. In some examples, the video decoder may include blocks within the current VPDU in the search area for other blocks within the current VPDU. For example, the video decoder may include blocks 904A, 904B, and 904C in the search area for block 904D. In some examples, the video decoder may include the VPDU shown as white (unshaded) in VPDU 902 in the search area for blocks of CTU 900, the above VPDU containing samples from a previously processed CTU (e.g., a CTU immediately preceding CTU 900 in decoding order).

[0147] Fig.10 is a conceptual diagram illustrating an example search area for CPR according to one or more techniques of this disclosure. Fig.10 As shown, CTU 1000 can be divided into four decoding blocks 1002A-1002D (collectively referred to as "decoding blocks 1002"). In some examples, decoding blocks 1002 can be referred to as VPDUs. For example, in the case where CTU 1000 includes 128×128 samples, CTU 1000 can be split into multiple VPDUs 1002, and each VPDU 602 can include 64×64 samples.

[0148] As described above, the video coder may include samples from a previously coded VPDU of the current CTU in a search region for the current VPDU of the current CTU (eg, for performing CPR). Fig.10As shown, the decoding order may be VPDU 1002A-1002B-1002C-1002D. In this example, the decoder may include VPDU 1002A in the search area for VPDU 1002B (e.g., VPDU 1002B may use VPDU 1002A for reference). The video decoder may include VPDU 1002A and VPDU 1002B in the search area for VPDU 1002C. The video decoder may include VPDUs 1002A-1002C in the search area for VPDU 1002D.

[0149] Fig.11 is a conceptual diagram illustrating an example search area for CPR according to one or more techniques of this disclosure. Fig.11 As shown, CTU 1100 can be divided into four decoding blocks 1102A-1102D (collectively referred to as "decoding blocks 1102"). In some examples, decoding blocks 1102 can be referred to as VPDUs. For example, in the case where CTU 1100 includes 128×128 samples, CTU 1100 can be split into multiple VPDUs 1102, and each VPDU 602 can include 64×64 samples.

[0150] As described above, the video coder may include samples from a previously coded VPDU of the current CTU in a search region for the current VPDU of the current CTU (eg, for performing CPR). Fig.11 As shown, the decoding order may be VPDU 1102A-1102C-1102B-1102D. In this example, the decoder may include VPDU 1102A in the search area for VPDU 1102C (e.g., VPDU 1102C may use VPDU 1102A for reference). The video decoder may include VPDU 1102A and VPDU 1102C in the search area for VPDU 1102B. The video decoder may include VPDUs 1102A-1102C in the search area for VPDU 1102D.

[0151] According to the fourth technology of the present disclosure, the video decoder may include a combination of samples from neighboring CTUs and samples from other coding blocks in the current CTU in the search area for the coding blocks in the current CTU. For example, the CPR search area of ​​the VPDU may include neighboring samples and reconstructed areas located within the current VPDU. The configuration and / or definition of the reference area that may be used for CPR, which may include neighboring samples and the size of the reference area, may depend on the location of the VPDU within the CTU.

[0152] Figures 12A-12Dis a conceptual diagram illustrating an example search area for performing CPR for various coding blocks of a CTU, in accordance with one or more techniques of this disclosure. Fig. 12A -12D each shows that the current CTU 1200 can be divided into four decoding blocks 1202A-1202D (collectively referred to as "decoding blocks 1202"). In some examples, the decoding block 1202 can be referred to as a VPDU. For example, in the case where the CTU 1200 includes 128×128 samples, the CTU 1200 can be split into multiple VPDUs 1202, and each VPDU 602 can include 64×64 samples. Figures 12A-12D The shaded area in each of may represent a search area for the current block. Fig. 12A In each of -12D, the shadow area (and therefore the search area) may include upper rows 1204 (eg, n upper rows) and left columns 1206 (eg, m left columns). The positions of the upper rows 1204 and left columns 1206 may change based on the position of the current block.

[0153] Fig. 12A An example search area for decoding block 1202A, also referred to as the upper left decoding block, is shown. Fig. 12A As shown in , the top row 1204 and the left column 1206 may both be located outside the CTU 1200.

[0154] Fig. 12B An example search area for decoding block 1202A, also referred to as the upper right decoding block, is shown. Fig. 12B As shown in , the top row 1204 can be located outside the CTU 1200, while the left column 1206 can be at least partially located inside the CTU 1200.

[0155] Fig. 12C An example search area for decoding block 1202A, also referred to as the lower left decoding block, is shown. Fig. 12C As shown in , the left column 1206 can be located outside the CTU 1200, while the upper row 1204 can be at least partially located inside the CTU 1200.

[0156] Fig.12D An example search area for decoding block 1202A, also referred to as the lower right decoding block, is shown. Fig.12D As shown in , the top row 1204 and the left column 1206 may both be located within the CTU 1200 .

[0157] In one example, M, N, m, and n rows may range from 1 to 4 (inclusive). As previously described, in another example, M, N, m, and n may be determined by the number of rows required by other tools such as interpolation prediction and deblocking filters.

[0158] In another example, the M and N rows outside the CTU may have different counts than the m and n rows inside the CTU. For example, M and N may be equal to 1, while m and n may be equal to 4.

[0159] In various examples, the above techniques may be applied to other CTU and VPDU sizes. For example, the CTU size may be 256. In another example, the VPDU size may be 32×32. Other VPDU and CTU sizes may also be used in conjunction with the above techniques.

[0160] Fig.13 2 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 Figure 4 ), but it should be understood that other devices may be configured to perform similar Fig.13 The method of the method.

[0161] In this example, the video encoder 200 initially predicts a current block (350). For example, the video encoder 200 may form a predictor block for the current block. For example, where the current block is a current coding block of a plurality of coding blocks of a current coding tree unit (CTU), the video encoder 200 may determine a corresponding search area in a plurality of corresponding search areas for each corresponding coding block in the plurality of coding blocks. In some examples, the search areas in the plurality of search areas may all be different. In some examples, at least one search area in the plurality of search areas includes samples of the current picture that are located outside the current CTU. In some examples, at least one search area in the plurality of search areas does not include samples of the current picture that are located outside the current CTU.

[0162] Video encoder 200 may then calculate a residual block for the current block (352). To calculate the residual block, video encoder 200 may calculate the difference between the original, unencoded block and the predictor block for the current block. Video encoder 200 may then transform and quantize coefficients of the residual block (354). Video encoder 200 may then scan the quantized transform coefficients of the residual block (356). During or after the scan, video encoder 200 may entropy encode the transform coefficients (358). For example, video encoder 200 may encode the transform coefficients using CAVLC or CABAC. Video encoder 200 may then output entropy encoded data for the block (360).

[0163] Fig.14 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 Figure 5 ), but it should be understood that other devices may be configured to perform similar Fig.14The method of the method.

[0164] The video decoder 300 may receive entropy coded data for a current block, such as entropy coded prediction information and entropy coded data corresponding to coefficients of a residual block of 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), for example, using an intra-frame or inter-frame prediction mode indicated by the prediction information of the current block to calculate a predictor block for the current block. For example, in the case where the current block is a current decoding block of multiple decoding blocks of a current decoding tree unit (CTU), the video decoder 300 may determine a corresponding search area of ​​multiple corresponding search areas for each corresponding decoding block of the multiple decoding blocks. In some examples, the search areas of the multiple search areas may all be different. In some examples, at least one search area of ​​the multiple search areas includes samples of the current picture located outside the current CTU. In some examples, at least one search area of ​​the multiple search areas does not include samples of the current picture located outside the current CTU.

[0165] The video decoder 300 may then inverse scan the reproduced coefficients (376) to create a quantized transform coefficient block. The video decoder 300 may then inverse quantize and inverse transform the transform coefficients to generate a residual block (378). The video decoder 300 may ultimately decode the current block (380) by combining the predictor block and the residual block.

[0166] Fig.15 1 is a flow chart illustrating an example method for predicting a block of video data in a current picture using a hybrid search region according to the techniques of this disclosure. The current block may include a current coding block of a current coding tree unit (CTU). Although relative to the video encoder 200 ( Figure 1 and Figure 4 ), but it should be understood that other devices may be configured to perform similar Fig.15 For example, the video decoder 300 ( Figure 1 and 5 ) can be configured to do something like Fig.15 The method of the method.

[0167] The video encoder 200 may determine a corresponding search area for each of a plurality of decoding blocks of a current CTU of a current picture (1502). Figure 8 Each of the decoding blocks 802 of the CTU determines a different search area. The various search areas may be considered as hybrid search areas, because some search areas include samples located outside the current CTU and some search areas do not include samples located outside the current CTU.

[0168] At least one of the multiple search areas may include at least some samples of the current picture located outside the current CTU. For example, the corresponding search areas for decoding block 802A (e.g., upper left decoding block), decoding block 802B (e.g., upper right decoding block), and decoding block 802C (e.g., lower left decoding block) may include samples of the current picture located outside CTU 800. As an example, the corresponding search areas for the upper left decoding block and the lower left decoding block may include samples of the current picture located in a left adjacent CTU of the current CTU.

[0169] At least one of the multiple search areas may not include samples of the current picture located outside the current CTU. For example, the corresponding search area for the decoding block 802D (e.g., the bottom right decoding block) may not include samples of the current picture located outside the CTU 800. As an example, the corresponding search area for the bottom right decoding block may include the top left decoding block, the top right decoding block, and the bottom left decoding block.

[0170] The video encoder 200 may select, for each coded block, a corresponding predictor block from a corresponding search region of the coded block (1504). For example, the video encoder 200 may select, from the search region for coded block 802A, a block that includes samples that most closely match samples of coded block 802A (e.g., will produce the smallest residual value), select, from the search region for coded block 802B, a block that includes samples that most closely match samples of coded block 802B, select, from the search region for coded block 802C, a block that includes samples that most closely match samples of coded block 802C, and select, from the search region for coded block 802D, a block that includes samples that most closely match samples of coded block 802D.

[0171] The video encoder 200 may determine a corresponding vector for each coded block, each corresponding vector identifying a corresponding predictor block for the corresponding coded block. For example, the video encoder 200 may determine a motion vector (also referred to as a block vector) representing a displacement between the coded block 802A and the predictor block of the coded block 802A. The motion vector may have a horizontal component representing a horizontal displacement between the coded block 802A and the predictor block of the coded block 802A, and a vertical component representing a vertical displacement between the coded block 802A and the predictor block of the coded block 802A.

[0172] The video encoder 200 may encode a representation of the vector in the decoded video bitstream. For example, the motion compensation unit 224 may select a motion vector predictor (MVP) and subtract the determined motion vector from the MVP to determine a motion vector difference (MVD). The motion compensation unit 224 may cause the entropy coding unit 220 to encode one or more syntax elements representing the MVD value in the decoded video bitstream. The video encoder 200 may similarly determine and encode a motion vector for each of the decoded blocks 802B-802D.

[0173] The video encoder 200 may reconstruct samples for each coded block (1506). For example, as part of a reconstruction loop, the video encoder 200 may add samples of the selected predictor block of the coded block 802A to the residual data to reconstruct the values ​​of the coded block 802A. The video encoder 200 may similarly reconstruct samples of the coded blocks 802B-802D (e.g., based on their respective predictor blocks and respective residual data).

[0174] It should be appreciated that, depending on the example, 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 for the practice of the techniques). Additionally, in some examples, actions or events may be performed simultaneously, such as through multithreading, interrupt handling, or multiple processors, rather than sequentially.

[0175] 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 corresponding 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) a non-transitory tangible computer-readable storage medium, or (2) a communication medium such as a signal or carrier wave. Data storage media may be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, codes, and / or data structures to implement the techniques described in the present disclosure. A computer program product may include a computer-readable medium.

[0176] As an example and not limitation, such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage devices, disk storage devices or other magnetic storage devices, flash memory or any other medium that can be used to store the desired program code in the form of instructions or data structures and can be accessed by a computer. In addition, any connection is properly referred to as a computer-readable medium. For example, if a coaxial cable, optical cable, twisted pair, digital subscriber line (DSL), or wireless technology (such as infrared, radio, and microwave) is used to send instructions from a website, server, or other remote source, then the coaxial cable, optical cable, twisted pair, DSL, or wireless technology (such as infrared, radio, and microwave) is included in the definition of the 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 point to non-temporary tangible storage media. The optical disk and disk used herein include compact discs (CDs), laser discs, optical optical discs, digital versatile discs (DVDs), floppy disks, and blue-ray discs, wherein the disks usually reproduce data magnetically, and the optical discs reproduce data optically with lasers. The above combination should also be included in the scope of computer-readable media.

[0177] 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 circuit systems. Therefore, the term "processor" used herein may refer to any of the aforementioned structures or any other structure suitable for implementing the techniques described herein. In addition, in some aspects, the functions described herein may be provided in dedicated hardware and / or software modules configured for encoding and decoding, or incorporated in a combined encoder / decoder. Similarly, these techniques may be implemented entirely in one or more circuits or logic elements.

[0178] The techniques of the present disclosure may be implemented in a 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 the present 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. Instead, as described above, the various units may be combined in an encoder / decoder 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.

[0179] 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, for each corresponding coding block in a plurality of coding blocks of a current coding tree unit (CTU) of the video data in a current picture of the video data, a corresponding search area in a plurality of corresponding search areas, wherein each corresponding search area in the plurality of search areas is different between each corresponding coding block of the current CTU, wherein at least one search area in the plurality of search areas includes samples of the current picture located outside the current CTU, and wherein at least one search area in the plurality of search areas does not include samples of the current picture located outside the current CTU; for each respective decoding block and from within the respective search area for the respective decoding block, selecting a respective predictor block from a plurality of predictor blocks; as well as Samples of each respective coding block are reconstructed based on samples included in a corresponding predictor block among the plurality of predictor blocks. 2 . The method according to claim 1 , wherein the plurality of decoding blocks include an upper left decoding block, an upper right decoding block, a lower left decoding block, and a lower right decoding block.

3. The method of claim 2, wherein the respective search areas for the upper left decoding block, the upper right decoding block, and the lower left decoding block include samples of the current picture that are outside the current CTU. 4 . The method of claim 3 , wherein the corresponding search area for the bottom right coding block does not include samples of the current picture that are outside the current CTU. 5 . The method of claim 4 , wherein the respective search areas for the upper left decoding block and the lower left decoding block include samples of the current picture located in a left neighboring CTU of the current CTU. 6 . The method of claim 5 , wherein the corresponding search area for the bottom right decoding block includes the top left decoding block, the top right decoding block, and the bottom left decoding block.

7. The method of claim 1, wherein each of the coded blocks comprises a 64x64 block of samples of video data.

8. The method of claim 7, wherein each of the decoding blocks comprises a virtual pipeline data unit (VPDU).

9. The method according to claim 1, further comprising: decoding, from a video bitstream and for each respective coded block of the plurality of coded blocks, one or more syntax elements representing a value of a vector identifying the selected predictor block, Wherein selecting the predictor block for the corresponding coding block comprises: selecting the predictor block based on the value of the vector.

10. The method according to claim 1, further comprising: One or more syntax elements are encoded in the video bitstream and for each respective coded block of the plurality of coded blocks, the syntax elements representing a value of a respective vector identifying the selected predictor block.

11. The method of claim 1, wherein the method is performed by a Versatile Video Coding (VVC) video coder.

12. A device for decoding video data, the device comprising: a memory configured to store the video data; as well as One or more processors implemented in circuitry and configured to: determining, for each corresponding coding block in a plurality of coding blocks of a current coding tree unit (CTU) of the video data in a current picture of the video data, a corresponding search area of ​​a plurality of corresponding search areas, wherein each corresponding search area of ​​the plurality of search areas is different between each corresponding coding block of the current CTU, wherein at least one search area of ​​the plurality of search areas includes samples of the current picture located outside the current CTU, and wherein at least one search area of ​​the plurality of search areas does not include samples of the current picture located outside the current CTU; for each respective decoding block and from within the respective search area for the respective decoding block, selecting a respective predictor block from a plurality of predictor blocks; as well as Samples of each respective coding block are reconstructed based on samples included in a corresponding predictor block among the plurality of predictor blocks.

13. The apparatus of claim 12, wherein the plurality of coding blocks comprises a top left coding block, a top right coding block, a bottom left coding block, and a bottom right coding block.

14. The apparatus of claim 13, wherein the respective search areas for the upper left decoding block, the upper right decoding block, and the lower left decoding block include samples of the current picture that are outside the current CTU.

15. The apparatus of claim 14, wherein the corresponding search area for the bottom right coding block does not include samples of the current picture that are outside the current CTU. 16 . The apparatus of claim 15 , wherein the corresponding search areas for the upper left coding block and the lower left coding block include samples of the current picture located in a left neighboring CTU of the current CTU.

17. The apparatus of claim 16, wherein the corresponding search area for the bottom right decoding block includes the top left decoding block, the top right decoding block, and the bottom left decoding block.

18. The apparatus of claim 12, wherein each of the coded blocks comprises a 64x64 block of samples of video data.

19. The apparatus of claim 18, wherein each of the decoding blocks comprises a virtual pipeline data unit (VPDU).

20. The device of claim 12, wherein the one or more processors are further configured to: decoding, from a video bitstream and for each respective coded block of the plurality of coded blocks, one or more syntax elements representing a value of a vector identifying the selected predictor block, in, To select the predictor block for a corresponding coding block, the one or more processors are configured to select the predictor block based on the value of the vector.

21. The device of claim 12, wherein the one or more processors are further configured to: One or more syntax elements are encoded in the video bitstream and for each respective coded block of the plurality of coded blocks, the syntax elements representing a value of a respective vector identifying the selected predictor block.

22. The apparatus of claim 12, wherein the apparatus is a Versatile Video Coding (VVC) video coder.

23. A video decoder, comprising: means for determining, for each corresponding coding block in a plurality of coding blocks of a current coding tree unit (CTU) of the video data in a current picture of the video data, a corresponding search area of ​​a plurality of corresponding search areas, wherein each corresponding search area of ​​the plurality of search areas is different between each corresponding coding block of the current CTU, wherein at least one search area of ​​the plurality of search areas includes samples of the current picture located outside the current CTU, and wherein at least one search area of ​​the plurality of search areas does not include samples of the current picture located outside the current CTU; means for selecting, for each respective decoding block and from within said respective search area for said respective decoding block, a respective predictor block from a plurality of predictor blocks; as well as Means for reconstructing samples of each respective coding block based on samples included in a corresponding predictor block in the plurality of predictor blocks.

24. A computer-readable storage medium having stored thereon instructions which, when executed, cause one or more processors to: determining, for each corresponding coding block in a plurality of coding blocks of a current coding tree unit (CTU) of the video data in a current picture of the video data, a corresponding search area in a plurality of corresponding search areas, wherein each corresponding search area in the plurality of search areas is different between each corresponding coding block of the current CTU, wherein at least one search area in the plurality of search areas includes samples of the current picture located outside the current CTU, and wherein at least one search area in the plurality of search areas does not include samples of the current picture located outside the current CTU; for each respective decoding block and from within the respective search area for the respective decoding block, selecting a respective predictor block from a plurality of predictor blocks; as well as Samples of each respective coding block are reconstructed based on samples included in a corresponding predictor block among the plurality of predictor blocks.

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