Surround Motion Compensation in Video Codecs

Abstract

Techniques for surround motion compensation are described to better ensure that parameters for performing surround motion compensation are available in a common parameter set. A video encoder may signal and a video decoder may parse a syntax element in a picture parameter set (PPS) that indicates an offset for surround motion compensation of a current block of video data.

Description

[0001] This application claims priority to U.S. Application No. 16 / 934,483, filed on July 21, 2020, which claims the benefit of U.S. Provisional Application No. 62 / 877,751, filed on July 23, 2019, the entire contents of each 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 integrated into a variety 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 radio telephones, so-called "smart phones", video teleconferencing devices, video streaming devices, etc. Digital video devices implement video codec technologies, 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 Codec (AVC), ITU-T H.265 / High Efficiency Video Codec (HEVC), and extensions of such standards. By implementing such video codec technologies, 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 codec tree units (CTUs), codec units (CUs), and / or codec nodes. Video blocks in an intra-coded (I) slice of a picture are encoded using spatial prediction for reference samples in neighboring blocks in the same picture. Video blocks in an inter-coded (P or B) slice of a picture may use spatial prediction for reference samples in neighboring blocks in the same picture, or temporal prediction for 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 surround motion compensation. The present disclosure describes example techniques for better ensuring that parameters used to perform surround motion compensation are available in a common parameter set so that video processing resources are not wasted accessing information from different parameter sets. The techniques of the present disclosure may also reduce delays in video processing caused by waiting for data from different parameter sets. The present disclosure also describes example techniques related to chroma formatting.

[0006] In one example, the present disclosure describes a method for decoding video data, the method comprising parsing a syntax element in a picture parameter set (PPS) indicating an offset for surround motion compensation of a current block of the video data, and performing inter-frame prediction decoding on the current block based on the offset for surround motion compensation.

[0007] In one example, the present disclosure describes a device for decoding video data, the device including a memory configured to store syntax elements of a picture parameter set (PPS), and processing circuitry configured to parse the syntax elements in the PPS indicating an offset for surround motion compensation of a current block of the video data, and perform inter-frame prediction decoding on the current block based on the offset for surround motion compensation.

[0008] In one example, the present disclosure describes a method of encoding video data, the method comprising inter-frame prediction encoding a current block of the video data based on an offset for surround motion compensation, and signaling a syntax element indicating the offset for surround motion compensation for the current block in a picture parameter set (PPS).

[0009] In one example, the present disclosure describes a device for encoding video data, the device including a memory configured to store syntax elements of a picture parameter set (PPS), and processing circuitry configured to inter-predictively encode a current block of the video data based on an offset for surround motion compensation, and to signal in the PPS a syntax element indicating the offset for surround motion compensation for the current block.

[0010] In one example, the present disclosure describes an apparatus for decoding video data, the apparatus including components for parsing a syntax element in a picture parameter set (PPS) indicating an offset for surround motion compensation of a current block of the video data, and components for inter-prediction decoding of the current block based on the offset for surround motion compensation.

[0011] In one example, the present disclosure describes a computer-readable storage medium having instructions stored thereon that, when executed, cause one or more processors to: parse a syntax element in a picture parameter set (PPS) that indicates an offset for surround motion compensation of a current block of video data, and perform inter-frame prediction decoding on the current block based on the offset for surround motion compensation.

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

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

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

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

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

[0017] Figure 5 is a flow chart illustrating an example method for encoding a current block of video data.

[0018] Figure 6 is a flow chart illustrating an example method for decoding a current block of video data. DETAILED DESCRIPTION

[0019] This disclosure describes example techniques related to surround motion compensation, and in some examples, surround motion compensation using reference picture resampling. This disclosure also describes techniques related to chroma formatting.

[0020] Surround motion compensation can be used in encoding and decoding omnidirectional video content (also known as 360° video content). Surround motion compensation uses video content that surrounds the 360° video content for inter-frame prediction. For example, a video codec (e.g., a video encoder or a video decoder) can generate a prediction block for inter-frame prediction of a current block based on samples along opposing boundaries of a reference picture. For example, the prediction block can include samples from a portion of a reference picture that extends beyond the left boundary of the reference picture and wraps around to the right boundary of the reference picture. In this example, the prediction block includes samples near the left boundary of the reference picture and samples from near the right boundary of the reference picture.

[0021] In reference picture resampling, the resolution of one or more reference pictures in the reference picture list may be different from the resolution of the current picture including the current block being inter-predicted. In some examples, in reference picture resampling, a surround motion compensation process may be used. However, even if reference picture resampling is not performed, a surround motion compensation process may be performed.

[0022] For surround motion compensation, a syntax element indicating whether a surround motion compensation process is enabled is signaled in a specific parameter set. However, some prior art techniques utilize parameter values ​​from one parameter set to determine whether to signal a syntax element indicating whether a surround motion compensation process is enabled in a different parameter set. That is, in these prior art techniques, in order to parse one parameter set to determine whether a surround motion compensation process is enabled, another parameter set needs to be accessed. In addition, a syntax element indicating an offset for surround motion compensation may be signaled in the same parameter set as a syntax element indicating whether a surround motion compensation process is enabled.

[0023] In those techniques, there may be certain problems. For example, a video codec (e.g., a video decoder) may need to access multiple different parameter sets to determine the value of a syntax element indicating whether a surround motion compensation process is enabled. Accessing different parameter sets may affect processing time because the parameter sets may be stored in different locations and may be stored off-chip. As another example, from the perspective of a video decoder, the video decoder may need to wait until multiple parameter sets are received before the video decoder can determine whether a surround motion compensation process is enabled.

[0024] This disclosure describes example techniques for better ensuring that parameters used to determine whether a surround motion compensation process is enabled are available in a common parameter set (if needed). In this way, the example techniques provide practical applications for video codecs that can improve the computational efficiency and operation of video codecs.

[0025] This disclosure also describes example techniques that may be applied to chroma formatting.For example, this disclosure describes examples of syntax elements for deriving a consistency window that is signaled in examples of parameter sets.

[0026] Figure 1 1 is a block diagram illustrating an example video encoding and decoding system 100 that may perform the techniques of the present disclosure. The techniques of the present disclosure are generally directed to encoding and decoding (encoding and / or decoding) video data. Generally, video data includes any data used to process video. Thus, video data may include original, unencoded video, encoded video, decoded (e.g., reconstructed) video, and video metadata (such as signaling data).

[0027] 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 target device 116. In particular, source device 102 provides the video data to target device 116 via computer-readable medium 110. Source device 102 and target device 116 may include any of a variety of devices, including desktop computers, notebooks (i.e., laptop computers), tablet computers, set-top boxes, handheld phones (such as smart phones), televisions, cameras, display devices, digital media players, video game consoles, video streaming devices, broadcast receiver devices, etc. In some cases, source device 102 and target device 116 may be equipped for wireless communication and, therefore, may be referred to as wireless communication devices.

[0028] exist Figure 1 In the example of, source device 102 includes video source 104, memory 106, video encoder 200 and output interface 108. Target device 116 includes input interface 122, video decoder 300, memory 120 and display device 118. According to the present disclosure, the video encoder 200 of source device 102 and the video decoder 300 of target device 116 can be configured to apply a technique for using reference picture resampling and syntax elements for deriving a consistency window to surround motion compensation. Thus, source device 102 represents an example of a video encoding device, and target device 116 represents an example of a video decoding device. In other examples, source device and target device may include other components or arrangements. For example, source device 102 may receive video data from an external video source such as an external camera. Similarly, target device 116 may be connected to an external display device via an interface without including an integrated display device.

[0029] like Figure 1The system 100 shown is only an example. Generally, any digital video encoding and / or decoding device can perform techniques for surrounding motion compensation using reference picture resampling and syntax elements for deriving a consistency window. The source device 102 and the target device 116 are only examples of such codec devices, wherein the source device 102 generates coded video data for transmission to the target device 116. The present disclosure represents a "codec" device as a device that performs the coding (coding and / or decoding) of data. Thus, the video encoder 200 and the video decoder 300 represent examples of codec devices, specifically, video encoders and video decoders, respectively. In some examples, the devices 102 and 116 can operate in a substantially symmetrical manner so that each of the devices 102 and 116 includes a video encoding and decoding component. Thus, the system 100 can support one-way or two-way video transmission between video devices 102 and 116, such as for video streaming, video playback, video broadcasting, or video telephony.

[0030] Typically, the video source 104 represents the source of video data (i.e., original, unencoded video data), and provides a series of continuous pictures (also referred to as "frames") of the video data to the video encoder 200, which encodes the data of the pictures. The video source 104 of the source device 102 may include a video capture device, such as a camera, a video archive including previously captured original video, and / or a video feed interface that receives video from a video content provider. As a further alternative, the 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, the video encoder 200 encodes the captured, pre-captured, or computer-generated video data. The video encoder 200 may rearrange the pictures from the receiving order (sometimes referred to as "display order") to the codec order for encoding and decoding. The video encoder 200 may generate a bitstream including encoded video data. Source device 102 may then output the encoded video data onto computer-readable medium 110 via output interface 108 , to be received and / or retrieved by, for example, input interface 122 of target device 116 .

[0031] The memory 106 of the source device 102 and the memory 120 of the target device 116 represent general purpose memory. In some examples, the memories 106, 120 can store original video data, such as the original video from the video source 104 and the 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 shown separately from the video encoder 200 and the video decoder 300 in this example, it should be understood that the video encoder 200 and the video decoder 300 can also include internal memory that achieves functionally similar or equivalent purposes. Further, 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.

[0032] The computer-readable medium 110 may represent any type of medium or device capable of transmitting the encoded video data from the source device 102 to the target device 116. In one example, the computer-readable medium 110 represents a communication medium for enabling the source device 102 to send the encoded video data directly to the target 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 equipment that facilitates communication from the source device 102 to the target device 116.

[0033] In some examples, source device 102 may output the encoded data from output interface 108 to storage device 112. Similarly, target device 116 may access the encoded data from storage device 112 via input interface 122. Storage device 112 may include any of a variety of distributed or locally accessed data storage media, such as a hard disk, Blu-ray disc, DVD, CD-ROM, flash memory, volatile or non-volatile memory, or any other suitable digital storage medium for storing encoded video data.

[0034] In some examples, source device 102 may output the encoded video data to file server 114 or another intermediate storage device that may store the encoded video data generated by source device 102. Target device 116 may access the stored video data from file server 114 via streaming or downloading.

[0035] The file server 114 may be any type of server device capable of storing encoded video data and sending the encoded video data to the target device 116. The file server 114 may represent a web server (e.g., for a website), a server configured to provide a file transfer protocol service (such as the File Transfer Protocol (FTP) or the File Delivery over Unidirectional Transport (FLUTE) protocol), a content delivery network (CDN) device, a hypertext transfer protocol (HTTP) server, a Multimedia Broadcast Multicast Service (MBMS) or enhanced MBMS (eMBMS) server, and / or a network attached storage (NAS) device. The file server 114 may additionally or alternatively implement one or more HTTP streaming protocols, such as Dynamic Adaptive Streaming over HTTP (DASH), HTTP Real-time Streaming (HLS), Real-time Streaming Protocol (RTSP), HTTP Dynamic Streaming, etc.

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

[0037] 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 the various 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), LTE Advanced, 5G, or the like. In certain 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 the IEEE 802.11 specification, the IEEE 802.15 specification (e.g., ZigBeeTM ), Bluetooth TM Standards, etc., to transmit data such as encoded video data. In some examples, source device 102 and / or target device 116 may include respective system-on-a-chip (SoC) devices. For example, source device 102 may include an SoC device to perform functions attributed to video encoder 200 and / or output interface 108, and target device 116 may include an SoC device to perform functions attributed to video decoder 300 and / or input interface 122.

[0038] The technology disclosed herein can be applied to video encoding and 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 to a data storage medium, decoding of digital video stored on a data storage medium, or other applications.

[0039] The input interface 122 of the target device 116 receives an encoded video bitstream from the computer-readable medium 110 (e.g., the storage device 112, the 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 characteristics and / or processing that describe video blocks or other coded and decoded units (e.g., slices, pictures, picture groups, sequences, etc.). The display device 118 displays decoded pictures of the decoded video data to the user. The display device 118 may represent any of a variety of display devices such as a cathode ray tube (CRT), a liquid crystal display (LCD), a plasma display, an organic light emitting diode (OLED) display, or another type of display device.

[0040] Although not in Figure 1 , but in some examples, each of the video encoder 200 and the video decoder 300 may 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 process multiplexed streams including audio and video 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).

[0041] Each of the video encoder 200 and the video decoder 300 can be implemented as any of a variety of suitable encoder and / or decoder circuits, such as one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), discrete logic, software, hardware, firmware, or any combination thereof. When the technology is partially implemented in software, the device can store instructions for the software in a suitable non-temporary computer-readable medium and use one or more processors to execute the instructions in hardware to perform the technology of the present disclosure. Each of the video encoder 200 and the video decoder 300 can be included in one or more encoders or decoders, both of which can be integrated as part of a combined encoder / decoder (CODEC) in the respective device. The device including the video encoder 200 and / or the video decoder 300 may include an integrated circuit, a microprocessor, and / or a wireless communication device such as a cellular phone.

[0042] The video encoder 200 and the video decoder 300 may operate according to a video codec standard such as ITU-T H.265, also known as High Efficiency Video Codec (HEVC), or an extension thereof such as a multi-view and / or scalable video codec extension. Alternatively, the video encoder 200 and the video decoder 300 may operate according to other proprietary or industry standards such as ITU-T H.266, also known as Versatile Video Codec (VVC). A draft of the VVC standard is described in "Versatile Video Codec (Draft 6)" by ITU-T SG 16 WP3 Joint Video Experts Group (JVET) and ISO / IEC JTC 1 / SC 29 / WG 11, 15th Meeting: Gothenburg, SE, July 3-12, 2019, JVET-O2001-vB, Bross et al. (hereinafter referred to as "VVC Draft 6"). A recent draft of the VVC standard is described in ITU-T SG 16 WP3 Joint Video Experts Group (JVET) and ISO / IEC JTC 1 / SC 29 / WG 11, 18th Meeting: by Teleconference, April 15-24, 2020, JVET-R2001-v8, Bross et al., "Versatile Video Codec (Draft 9)" (hereinafter referred to as "VVC Draft 9"). However, the techniques of the present disclosure are not limited to any particular coding standard.

[0043] In general, the video encoder 200 and the video decoder 300 can perform block-based encoding and decoding of pictures. The term "block" generally refers to a structure that includes data to be processed (e.g., encoded, decoded, or otherwise used in the encoding and / or decoding process). For example, a block may include a two-dimensional matrix of samples of luminance and / or chrominance data. In general, the video encoder 200 and the video decoder 300 can encode and decode video data represented in YUV (e.g., Y, Cb, Cr) format. That is, the video encoder 200 and the video decoder 300 can encode and decode luminance and chrominance components instead of encoding and decoding red, green, and blue (RGB) data of samples of the picture, where the chrominance components may include red and blue 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. Alternatively, a pre-processing and post-processing unit (not shown) can perform these conversions.

[0044] The present disclosure generally refers to the encoding and decoding of a picture (e.g., encoding and decoding), including the process of encoding or decoding picture data. Similarly, the present disclosure may refer to the encoding and 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 encoding and decoding. The encoded video bitstream generally includes syntax elements for representing codec decisions (e.g., codec modes) and a series of values ​​for partitioning the picture into blocks. Thus, references to encoding and decoding a picture or a block should generally be understood as encoding and decoding the values ​​of the syntax elements that form the picture or block.

[0045] HEVC defines various blocks, including codec units (CUs), prediction units (PUs), and transform units (TUs). According to HEVC, a video codec (such as video encoder 200) partitions a codec tree unit (CTU) into CUs according to a quadtree structure. That is, the video codec 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 a child node 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 codec may further partition the PU and TU. For example, in HEVC, the residual quadtree (RQT) represents the partitioning of the TUS. In HEVC, PU represents inter-frame prediction data and TU represents residual data. The intra-predicted CU includes intra-frame prediction information, such as an intra-frame mode indication.

[0046] As another example, the video encoder 200 and the video decoder 300 can be configured to operate according to VVC. According to VVC, a video codec (such as the video encoder 200) partitions a picture into multiple codec tree units (CTUs). The video encoder 200 can partition the CTU according to a tree structure (such as a quadtree-binary tree (QTBT) structure or a multi-type tree (MTT) structure). The QTBT structure eliminates the concept of multiple partition types, such as the distinction between CU, PU, ​​and TU of HEVC. The QTBT structure includes two levels: a first level partitioned according to quadtree partitioning, and a second level partitioned according to binary tree partitioning. The root node of the QTBT structure corresponds to the CTU. The leaf nodes of the binary tree correspond to codec units (CUs).

[0047] In the MTT partitioning structure, blocks can be partitioned using quadtree (QT) partitioning, binary tree (BT) partitioning, and one or more types of ternary tree (TT) partitioning. A ternary tree partitioning is a partitioning in which a block is divided into three sub-blocks. In some examples, a ternary tree partitioning divides a block into three sub-blocks without dividing the original block through the center. The partitioning types in MTT (e.g., QT, BT, and TT) can be symmetric or asymmetric.

[0048] 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 and chroma components, while in other examples, the video encoder 200 and the video decoder 300 may use two or more QTBT or MTT structures, such as one QTBT / MTT structure for the luma component and another QTBT / MTT structure for the two chroma components (or two QTBT / MTT structures for the corresponding chroma components).

[0049] The video encoder 200 and the video decoder 300 may be configured to use quadtree segmentation, QTBT segmentation, MTT segmentation, or other segmentation structures in accordance with HEVC. For purposes of illustration, a description of the techniques of the present disclosure is provided for QTBT segmentation. However, it should be understood that the techniques of the present disclosure may also be applied to video codecs configured to use quadtree segmentation or other types of segmentation.

[0050] 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 area of ​​a CTU row in a particular tile in a picture. A tile may be a rectangular area of ​​a CTU in a particular tile column and a particular tile row in a picture. A tile column refers to a rectangular area 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 tile row refers to a rectangular area 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.

[0051] In some examples, a tile may be partitioned into multiple bricks, each of which may include one or more CTU rows in the tile. A tile that is not partitioned into multiple bricks may also be referred to as a brick. However, a brick that is a proper subset of a tile may not be referred to as a tile.

[0052] Tiles in a picture can also be arranged in slices. A slice can be an integer number of tiles of a picture that can be uniquely contained in a single Network Abstraction Layer (NAL) unit. In some examples, a slice includes several complete tiles or only a continuous sequence of complete tiles of a tile.

[0053] The present disclosure may use "N×N" and "N times N" interchangeably to represent the sample dimensions of a block (such as a CU or other video block) in terms of vertical and horizontal dimensions, for example, 16×16 samples or 16 times 16 samples. Generally, a 16×16 CU will have 16 samples in the vertical direction (y=16) and 16 samples in the horizontal direction (x=16). Similarly, an N×N CU generally has N samples in the vertical direction and N samples in the horizontal direction, where N represents a non-negative integer value. The samples in a CU may be arranged in rows and columns. In addition, a CU does not necessarily have the same number of samples in the horizontal direction as in the vertical direction. For example, a CU may include N×M samples, where M is not necessarily equal to N.

[0054] 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 the CU will be predicted in order to form a prediction block for the CU. The residual information generally represents the sample-by-sample difference between the samples of the CU before encoding and the prediction block.

[0055] In order to predict a CU, the video encoder 200 can generally form a prediction block for the CU by inter-frame prediction or intra-frame prediction. Inter-frame prediction generally refers to predicting a CU from data of a previously coded picture, while intra-frame prediction generally refers to predicting a CU from previously coded data of the same picture. In order to perform inter-frame prediction, the video encoder 200 can use one or more motion vectors to generate a prediction block. The video encoder 200 can generally perform a motion search to identify a reference block that closely matches the CU, for example, in terms of the difference between the CU and the reference block. The video encoder 200 can use the sum of absolute differences (SAD), the sum of squared differences (SSD), the mean absolute difference (MAD), the mean square difference (MSD), or other such difference calculations to calculate a difference metric to determine whether the reference block closely matches the current CU. In some examples, the video encoder 200 can use unidirectional prediction or bidirectional prediction to predict the current CU.

[0056] In some examples, VVC may provide an affine motion compensation mode, which may be considered an inter-prediction mode. In the affine motion compensation mode, the video encoder 200 may determine two or more motion vectors representing non-translational motion, such as zooming in or out, rotation, perspective motion, or other irregular motion types.

[0057] In order to perform intra prediction, the video encoder 200 can select an intra prediction mode to generate a prediction block. In some examples, VVC can provide sixty-seven intra prediction modes, including modes of various directions as well as planar modes and DC modes. Generally, the video encoder 200 selects an intra prediction mode that describes neighboring samples of a current block (e.g., a block of a CU) to predict the prediction samples of the current block from it. Assuming that the video encoder 200 encodes and decodes CTUs and CUs in a raster scan order (from left to right, from top to bottom), such samples can typically be above, on the left, or on the left of the current block in the same picture as the current block.

[0058] 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 can encode data indicating which of various available inter-frame prediction modes is used and motion information of the corresponding mode. For unidirectional or bidirectional inter-frame prediction, for example, the video encoder 200 can encode the motion vector using advanced motion vector prediction (AMVP) or merge mode. The video encoder 200 can use a similar mode to encode the motion vector of the affine motion compensation mode.

[0059] 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 prediction block of the block, which is formed using a corresponding prediction mode. 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. Additionally, 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.

[0060] As described above, after performing any transforms to produce transform coefficients, the video encoder 200 can perform quantization on the transform coefficients. Quantization generally refers to the process of quantizing the transform coefficients to possibly reduce the amount of data used to represent the coefficients, thereby providing further compression. By performing the quantization process, the video encoder 200 can reduce the bit depth associated with some or all of the coefficients. For example, the video encoder 200 can round 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.

[0061] After quantization, the video encoder 200 can scan the transform coefficients to generate a one-dimensional vector according to the two-dimensional matrix including the quantized transform coefficients. The scan can be designed to place coefficients with higher energy (and therefore lower frequency) in front of the vector and transform coefficients with 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 values ​​for syntax elements, which describe metadata associated with the encoded video data used by the video decoder 300 in decoding the video data.

[0062] To perform CABAC, the video encoder 200 may assign context within a context model to a symbol to be transmitted. For example, the context may relate to whether the neighboring values ​​of the symbol are zero values. The probability determination may be based on the context assigned to the symbol.

[0063] The video encoder 200 may further 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 generate 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 similarly decode such syntax data to determine how to decode the corresponding video data.

[0064] In this way, the video encoder 200 can generate a bitstream including encoded video data, such as syntax elements describing the partitioning of a picture into blocks (eg, CUs) and prediction and / or residual information for the blocks. Finally, the video decoder 300 can receive the bitstream and decode the encoded video data.

[0065] In general, the video decoder 300 performs the reverse 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 (although reversed from) the CABAC encoding process of the video encoder 200. The syntax elements may define partitioning information regarding partitioning of a picture into CTUs and partitioning each CTU according to a corresponding partitioning structure such as a QTBT structure to define CUs of the CTU. The syntax elements may further define prediction and residual information for a block (e.g., a CU) of video data.

[0066] For example, the residual information may be represented by quantized transform coefficients. The video decoder 300 may inverse quantize and inverse transform the quantized transform coefficients of the block to reproduce the residual block of the block. The video decoder 300 uses the signaled prediction mode (intra-frame or inter-frame prediction) and related prediction information (e.g., motion information for inter-frame prediction) to form a prediction block for the block. The video decoder 300 may then combine the prediction block and the residual block (on a sample-by-sample basis) to reproduce the original block. The video decoder 300 may perform additional processes (such as performing a deblocking process) to reduce visual artifacts along the boundaries of the blocks.

[0067] In general, the present disclosure may refer to "signaling" certain information, such as syntax elements. The term "signaling" may generally refer to the communication of values ​​for syntax elements and / or other data used to decode the encoded video data. That is, the video encoder 200 may signal the values ​​of syntax elements in the bitstream. In general, signaling refers to generating values ​​in the bitstream. As described above, the source device 102 may transmit the bitstream to the target device 116 in substantially real time (or non-real time, such as may occur when storing syntax elements to the storage device 112 for later retrieval by the target device 116).

[0068] As described in more detail below, according to the techniques of the present disclosure, the video encoder 200 and the video decoder 300 can be configured to perform surround motion compensation, and in some examples, perform surround motion compensation using reference picture resampling and determining syntax elements for deriving a consistency window. As an example, the video encoder 200 can signal, and the video decoder 300 can parse, syntax elements for surround motion compensation (such as a portion of omnidirectional or 360° video content). In surround motion compensation, the video encoder 200 and the video decoder 300 can generate a prediction block based on a reference picture, wherein the prediction block includes samples from opposing boundaries of the reference picture.

[0069] For example, in wrap-around motion compensation, the motion vector of the current block may identify an area in the reference picture that extends beyond the border of the reference picture. As an example, the motion vector may refer to an area that extends beyond the left border of the reference picture. In an example using wrap-around motion compensation, the prediction block may include samples from the area of ​​the reference picture up to the left border and then wrap around to include samples from the right border of the reference picture. Wrap-around motion compensation may also be referred to as horizontal wrap-around motion compensation.

[0070] According to one or more examples described in the present disclosure, one or more syntax elements for surround motion compensation may be included in the same parameter set, such as a picture parameter set. In addition, one or more syntax elements for surround motion compensation that may not be in a picture parameter set may be signaled by the video encoder 200 or parsed by the video decoder 300, independent of any information available in the picture parameter set. For example, there may be syntax elements for surround motion compensation in a sequence parameter set. However, whether the syntax element is signaled or parsed in a sequence parameter set may not depend on any information in the picture parameter set. In this way, the video decoder 300 may be able to parse syntax elements of a parameter set without parsing syntax elements of another parameter set, which facilitates efficient video encoding and decoding (e.g., the video decoder 300 does not need to wait for all parameter sets before starting parsing, and when parsing a parameter set, the video decoder 300 does not need to perform additional memory accesses for another parameter set).

[0071] The video codec (e.g., the video encoder 200 or the video decoder 300) may be configured to encode and decode (e.g., the video encoder 200 may signal and the video decoder 300 may parse) information for determining whether to apply surround motion compensation in a parameter set (e.g., pic_width_luma_samples in a PPS or max_width_in_luma_samples in an SPS) and to encode and decode a syntax element indicating whether surround motion compensation is applied in the same parameter set (e.g., ref_wraparound_enabled_flag in a PPS when pic_width_luma_samples is used or ref_wraparound_enabled_flag in an SPS when max_width_in_luma_samples is used). When the ref_wraparound_enabled_flag is part of the PPS, the ref_wraparound_enabled may be referred to as pps_ref_wraparound_enabled_flag. When the ref_wraparound_enabled_flag is part of the SPS, the ref_wraparound_enabled may be referred to as sps_ref_wraparound_enabled_flag.

[0072] In some examples, the video codec can be configured to encode (e.g., the video encoder 200 can signal and the video decoder 300 can parse) a syntax element indicating whether wrap motion compensation is applied regardless of the picture width in terms of the number of luma samples (e.g., regardless of the picture width). For example, whether sps_ref_wraparound_enabled_flag or pps_ref_wraparound_enabled_flag is signaled is not based on the value of pic_width_luma_samples.

[0073] In some examples, the video codec may be configured to encode and decode information used to derive the consistency window using any or a combination of techniques described in this disclosure.For example, this disclosure describes examples regarding chroma_format_idc and separate_colour_plane flag syntax elements.

[0074] In "AHG8: Integrated specification text for reference picture resampling" (hereinafter referred to as "JVET-O1164"), Chen et al., ITU-T SG 16 WP3 Joint Video Experts Group (JVET) and ISO / IEC JTC 1 / SC 29 / WG 11, 15th meeting: Gothenburg, SE, July 3-12, 2019, JVET-O1164, Reference Picture Resampling (RPR) was proposed. In the proposal, the current picture and the reference picture may have different resolutions. Therefore, during motion compensation, the difference in resolution is taken into account during interpolation filtering by adjusting the interpolation filter phase.

[0075] sps_ref_wraparound_enabled_flag indicates the presence of wraparound motion compensation.

[0076]

[0077] In the above, CtbSizeY is the height of the codec treeblock (maximum codec block size), MinCbSizeY indicates the minimum codec block size, and pic_width_in_luma_samples indicates the picture width of the picture (eg, in number of luma samples).

[0078] In some examples, sps_ref_wraparound_enabled_flag equal to 1 specifies that horizontal wrap motion compensation is applied in inter prediction, while sps_ref_wraparound_enabled_flag equal to 0 specifies that horizontal wrap motion compensation is not applied. When not present, the value of sps_ref_wraparound_enabled_flag is inferred to be equal to 0.

[0079] In some examples, sps_ref_wraparound_offset_minus1 plus 1 specifies an offset for calculating the horizontal wrapping position in units of MinCbSizeY luma samples. The value of ref_wraparound_offset_minus1 may be in the range of (CtbSizeY / MinCbSizeY)+1 to (pic_width_in_luma_samples / MinCbSizeY)-1, inclusive.

[0080] In JVET-O1164, picture size signaling is moved from the SPS to the PPS, but sps_ref_wraparound_enabled_flag still depends on the picture size indicated by pic_width_in_luma_samples, which no longer exists in the SPS. For example, in the syntax above, whether sps_ref_wraparound_enabled_flag is signaled in the SPS, and similarly, whether sps_ref_wraparound_offset_minus1 is signaled in the SPS depends on the value of pic_width_in_luma_samples. However, the syntax element pic_width_in_luma_samples may exist in the PPS instead of the SPS. Therefore, the video decoder 300 may need to parse the PPS to determine the value of pic_width_in_luma_samples to determine whether to parse sps_ref_wraparound_enabled_flag and sps_ref_wraparound_offset_minus1.

[0081] Therefore, there may be technical issues in determining whether wraparound motion compensation is enabled based on information in different parameter sets (e.g., pic_width_in_luma_samples is available in PPS, but sps_ref_wraparound_enabled_flag is in SPS). As described above, requiring different parameter sets may result in delays in decoding and processing overhead from memory access.

[0082] This disclosure describes example solutions to these problems.The example techniques may be used alone or in any combination.

[0083] In the SPS, the video encoder 200 may be configured to signal, and the video decoder 300 may be configured to receive, the maximum picture size as follows:

[0084] max_width_in_luma_samples ue(v) max_height_in_luma_samples ue(v)

[0085] In one example, the video encoder 200 may be configured to signal and the video decoder 300 may be configured to receive the sps_ref_wraparound_enabled_flag, which depends on max_width_in_luma_samples instead of pic_width_in_luma_samples.

[0086] An example of implementation is provided below.

[0087]

[0088] In one example, the video encoder 200 may signal and the video decoder 300 may parse the syntax elements sps_ref_wraparound_enabled_flag and sps_ref_wraparound_offset_minus1 in the PPS. In these examples, the signaling condition (e.g., if ((CtbSizeY / MinCbSizeY+1)<=(max_width_in_luma_samples / MinCbSizeY-1))) may remain unchanged because pic_width_in_luma_samples is signaled in the PPS. However, requiring the condition to be checked (e.g., if ((CtbSizeY / MinCbSizeY+1)<=(max_width_in_luma_samples / MinCbSizeY-1))) may not be necessary in all examples. According to one or more examples described herein, instead of using the syntax elements sps_ref_wraparound_enabled_flag and sps_ref_wraparound_offset_minus1, the syntax elements may be referred to as pps_ref_wraparound_enabled_flag and pps_ref_wraparound_offset_minus1.

[0089] In some examples, the PPS may include pps_ref_wraparound_enabled_flag and pps_ref_wraparound_offset_minus 1. In such examples, the SPS may still include sps_ref_wraparound_enabled_flag to provide SPS level signaling indicating whether surround compensation is enabled.

[0090] Additionally, the video encoder 200 may signal and the video decoder 300 may parse the CTB size (CtbSizeY) and the minimum CB size (MinCbSizeY) from the PPS, since CtbSizeY and MinCbSizeY are used in the sps_ref_wraparound_enabled_flag signaling. Those syntax elements may be additionally signaled in the PPS, rather than being signaled or received from the SPS, where the semantics of the PPS syntax elements are constrained so that the CtbSizeY and MinCbSizeY signaled in the PPS should be the same or equal to the syntax elements (e.g., CtbSizeY and MinCbSizeY) signaled in the SPS. In other words, one or more or all of ref_wraparound_enabled_flag, ref_wraparound_offset_minus1, CtbSizeY, and MinCbSizeY may be signaled in both the SPS and the PPS as copies of each other, but may not be required to be copies of each other.

[0091] For example, as described above, the PPS may include a ref_wraparound_enabled_flag (e.g., pps_ref_wraparound_enabled_flag), and the SPS may include a ref_wraparound_enabled_flag (e.g., sps_ref_wraparound_enabled_flag). In some examples, the pps_ref_wraparound_enabled_flag and the sps_ref_wraparound_enabled_flag may be copies of each other. However, in some examples, the pps_ref_wraparound_enabled_flag and the sps_ref_wraparound_enabled_flag may be different. For example, at a sequence level, wraparound motion compensation may be enabled (e.g., sps_ref_wraparound_enabled_flag may be true), but at a picture level for a particular picture, wraparound motion compensation may be disabled (e.g., pps_ref_wraparound_enabled_flag may be false).

[0092] As described above, some technologies require that the signaling of sps_ref_wraparound_enabled_flag must satisfy the following condition: “if ((CtbSizeY / MinCbSizeY+1)<=(pic_width_in_luma_samples / MinCbSizeY-1))”. As described above, this condition may cause technical problems since pic_width_in_luma_samples is not available in SPS.

[0093] In some examples, as described above, the SPS may include a sps_ref_wraparound_enabled_flag. To ensure that parsing the sps_ref_wraparound_enabled_flag from the SPS does not require access to the PPS, the condition "if ((CtbSizeY / MinCbSizeY+1)<=(pic_width_in_luma_samples / MinCbSizeY-1))" may be removed from the sps_ref_wraparound_enabled_flag signaling notification. For example, the video encoder 200 and the video decoder 300 may encode and decode a syntax element indicating whether surround motion compensation (e.g., ref_wraparound_enabled_flag) is applied regardless of the picture width (such as in terms of the number of luma samples) (e.g., regardless of pic_width_in_luma_samples).

[0094] In one or more examples, the semantics of sps_ref_wraparound_enabled_flag can be constrained such that if (CtbSizeY / MinCbSizeY+1)>(pic_width_in_luma_samples / MinCbSizeY-1) then sps_ref_wraparound_enabled_flag should be equal to 0. This can be considered the opposite condition of the sps_ref_wraparound_enabled_flag signaling. In other words, if sps_ref_wraparound_enabled_flag indicates that surround compensation is enabled (e.g., sps_ref_wraparound_enabled_flag is 1), then (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1). In this way, if sps_ref_wraparound_enabled_flag is 1, then for a compliant bitstream, (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1).

[0095] Additionally or alternatively, in addition to or instead of the SPS, the video encoder 200 may signal and the video decoder 300 may parse the chroma format IDC chroma_format_idc and separate_colour_plane_flag from the PPS.

[0096] Instead of signaling or parsing from the SPS, chroma_format_idc and optionally separate_colour_plane_flag may be additionally signaled in the PPS, wherein the semantics of chroma_format_idc and separate_colour_plane_flag in the PPS are restricted such as they shall be the same or equal to the chroma_format_idc and separate_colour_plane_flag signaled in the SPS, respectively.

[0097]

[0098]

[0099] In some examples, chroma_format_idc specifies the chroma samples relative to the luma samples specified in VVC draft 6 clause 6.2. The value of chroma_format_idc can be in the range of 0 to 3 (inclusive). In some examples, separate_colour_plane_flag equal to 1 specifies that the three color components of the 4:4:4 chroma format are encoded and decoded separately, while separate_colour_plane_flag equal to 0 specifies that these color components are not encoded and decoded separately. When separate_colour_plane_flag is not present, it is inferred to be equal to 0. When separate_colour_plane_flag is equal to 1, the encoded picture consists of three independent components, each component consists of encoded samples of one color plane (Y, Cb or Cr), and uses the monochrome codec syntax. In this case, each color plane is associated with a specific colour_plane_id value.

[0100] In one or more examples, chroma_format_idc is used to derive the consistency window, which is moved to the PPS in JVET-O01164. The chroma format IDC is used to derive the scaling factor of the consistency window (SubWidthC in the VVC specification). In some cases, retaining the chroma format IDC in the SPS creates a dependency in the consistency window derivation. In this case, the derivation at the slice level can only be done if the PPS and SPS used in the slice are known. If chroma_format_idc is signaled to the PPS or is additionally signaled in the PPS, the consistency window can be derived at the PPS resolution, which may be preferred in cases where there are multiple PPSs and SPSs in the bitstream.

[0101] According to one or more examples described in the present disclosure, the video decoder 300 may parse a syntax element in a picture parameter set (PPS) indicating an offset for wraparound motion compensation of a current block of video data. For example, the video decoder 300 may parse pps_ref_wraparound_offset_minus1. It should be noted that pps_ref_wraparound_offset_minus1 is an example of a syntax element indicating an offset for wraparound motion compensation. However, there may be various examples of syntax elements in the PPS indicating an offset for wraparound motion compensation of the current block. As an example, a syntax element indicating the difference between a picture width and an offset may be a syntax element in the PPS indicating an offset for wraparound motion compensation of the current block. As another example, a syntax element indicating the actual value of the offset may be signaled in the PPS. There may be various ways to include information indicating the offset in the PPS, and the present disclosure should not be considered to be limited to pps_ref_wraparound_offset_minus1.

[0102] The syntax element in the PPS that indicates the offset for wraparound motion compensation of the current block of video data can be considered as a first syntax element. In some examples, the video decoder 300 can parse the second syntax element in the PPS that indicates whether wraparound motion compensation is enabled. An example of a second syntax element is pps_ref_wraparound_enabled_flag. For example, in order to parse the syntax element in the PPS that indicates the offset for wraparound motion compensation of the current block, the video decoder 300 can parse the first syntax element based on the second syntax element in the PPS that indicates that wraparound motion compensation is enabled. That is, the video decoder 300 can parse the pps_ref_wraparound_enabled_flag, and based on the pps_ref_wraparound_enabled_flag being true, the video decoder 300 can parse the syntax element in the PPS that indicates the offset for wraparound motion compensation of the current block.

[0103] In one or more examples, the SPS may further include a syntax element indicating whether wraparound compensation is enabled. For example, the SPS may include sps_ref_wraparound_enabled_flag (e.g., the video encoder 200 may encode the sps_ref_wraparound_enabled_flag in the SPS). In one or more examples, the video decoder 300 may parse a second syntax element in a sequence parameter set (SPS) indicating whether wraparound motion compensation is enabled (e.g., parse sps_ref_wraparound_enabled_flag) regardless of the picture width. The value of the second syntax element (e.g., sps_ref_wraparound_enabled_flag) indicating that wraparound motion compensation is enabled may be constrained based on the picture width, the minimum block size, and the maximum block size.

[0104] For example, the video decoder 300 may not need to determine whether the following condition is true: (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1). Instead, based on the second syntax element indicating that wraparound motion compensation is enabled (e.g., sps_ref_wraparound_enabled_flag), (CtbSizeY / MinCbSizeY+1) may have to be less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1). As described above, CtbSizeY is the height of the codec tree block (maximum codec block size), MinCbSizeY indicates the minimum codec block size, and pic_width_in_luma_samples indicates the picture width of the picture including the current block.

[0105] The video decoder 300 may be configured to perform inter-prediction decoding on the current block based on the offset for wrap motion compensation. For example, the video decoder 300 may generate a prediction block based on the offset for wrap motion compensation, and add the prediction block to the residual block to reconstruct the current block. The wrap offset specifies the offset by which the portion of the prediction block extending outside the picture is moved from the picture boundary when wrapping occurs. For example, the wrap offset may specify how much the prediction block extends on one boundary (e.g., the left boundary) and wraps around on another boundary (e.g., the right boundary). As an example, the wrap offset may be considered to be a vertical line near the left boundary of the picture and a vertical line near the right boundary. The vertical lines may define how much to wrap around to identify samples where the motion vector points to the portion of the prediction block extending on the boundary.

[0106] The video encoder 200 may perform operations similar to those of the video decoder 300, but for encoding. For example, the video encoder 200 may inter-prediction encode a current block of video data based on an offset for surround motion compensation. The video encoder 200 may generate a prediction block based on the offset for surround motion compensation, and signal information of a residual block indicating a difference between the prediction block and the current block.

[0107] In one or more examples, the video encoder 200 may signal a syntax element in a picture parameter set (PPS) indicating an offset for wraparound motion compensation for a current block. One example of a syntax element is pps_ref_wraparound_offset_minus1. However, there may be various examples of syntax elements in a PPS indicating an offset for wraparound motion compensation for a current block. As an example, a syntax element indicating the difference between a picture width and an offset may be a syntax element in a PPS indicating an offset for wraparound motion compensation for a current block. As another example, a syntax element indicating an actual value of the offset may be signaled in the PPS. There may be various ways to include information indicating the offset in a PPS, and the present disclosure should not be considered limited to pps_ref_wraparound_offset_minus1.

[0108] The syntax element in the PPS indicating the offset for wraparound motion compensation of the current block of video data can be considered as a first syntax element. The video encoder 200 can be configured to signal a second syntax element in the PPS indicating whether wraparound motion compensation is enabled. An example of a second syntax element is pps_ref_wraparound_enabled_flag. In these examples, in order to signal the syntax element indicating the offset for wraparound motion compensation for the current block in the PPS, the video encoder 200 can signal the first syntax element based on the second syntax element in the PPS indicating that wraparound motion compensation is enabled. That is, the video encoder 200 can signal pps_ref_wraparound_enabled_flag, and based on pps_ref_wraparound_enabled_flag being true, the video encoder 200 can signal the syntax element indicating the offset for wraparound motion compensation for the current block in the PPS.

[0109] In one or more examples, the SPS may further include a syntax element indicating whether wraparound compensation is enabled. For example, the SPS may include sps_ref_wraparound_enabled_flag. In one or more examples, the video encoder 200 may signal a second syntax element indicating whether wraparound motion compensation is enabled in a sequence parameter set (SPS) regardless of the picture width (e.g., signaling sps_ref_wraparound_enabled_flag). The value of the second syntax element (e.g., sps_ref_wraparound_enabled_flag) indicating that wraparound motion compensation is enabled may be constrained based on the picture width, the minimum block size, and the maximum block size.

[0110] For example, the video encoder 200 may not need to determine whether the following condition is true: (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1). Instead, based on the second syntax element indicating that wraparound motion compensation is enabled (e.g., sps_ref_wraparound_enabled_flag), (CtbSizeY / MinCbSizeY+1) may have to be less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1). As described above, CtbSizeY is the height of the codec tree block (maximum codec block size), MinCbSizeY indicates the minimum codec block size, and pic_width_in_luma_samples indicates the picture width of the picture including the current block.

[0111] Figure 2A and Figure 2Bis a conceptual diagram showing an example quadtree binary tree (QTBT) structure 130 and a corresponding codec tree unit (CTU) 132. Solid lines represent quadtree partitions and dashed lines indicate binary tree partitions. In each partition (i.e., non-leaf) node of the binary tree, a flag is signaled to indicate which partition type (i.e., horizontal or vertical) is used, where in this example, 0 indicates horizontal partitioning and 1 indicates vertical partitioning. For quadtree partitioning, since the quadtree node divides the block horizontally and vertically into 4 sub-blocks of equal size, there is no need to indicate the partition type. Accordingly, the video encoder 200 can encode syntax elements (e.g., partition information) at the regional tree level (i.e., solid line) of the QTBT structure 130 and syntax elements (e.g., partition information) at the prediction tree level (i.e., dashed line) of the QTBT structure 130, and the video decoder 300 can decode these syntax elements. For a CU represented by a terminal leaf node of the QTBT structure 130 , the video encoder 200 may encode video data (such as prediction and transform data), and the video decoder 300 may decode the video data.

[0112] Generally, Figure 2B The CTU 132 may be associated with parameters that define the size of blocks corresponding to nodes of the first and second level QTBT structures 130. These parameters may include a CTU size (indicating the size of the CTU 132 in samples), a minimum quadtree size (MinQTSize, indicating the minimum allowed quadtree leaf node size), a maximum binary tree size (MaxBTSize, indicating the maximum allowed binary tree root node size), a maximum binary tree depth (MaxBTDepth, indicating the maximum allowed binary tree depth), and a minimum binary tree size (MinBTSize, indicating the minimum allowed binary tree leaf node size).

[0113] The root node of the QTBT structure corresponding to the CTU can have four child nodes at the first level of the QTBT structure, and each child node can be segmented according to the quadtree segmentation. That is, the node of the first level is a leaf node (no child node) or has four child nodes. The example of the QTBT structure 130 represents such a node, which includes a child node and a parent node with a solid line branch. If the node of the first level is not larger than the maximum allowed binary tree root node size (MaxBTSize), the node can be further segmented by the corresponding binary tree. It is possible to iterate the binary tree partitioning of a node until the node generated by the partition 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 branch. The binary tree leaf node is represented as a codec 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 can also be represented as a "video block" or "block".

[0114] In one example of a QTBT partitioning structure, the CTU size is set to 128x128 (luminance sample and two corresponding 64x64 chrominance samples), MinQTSize is set to 16x16, MaxBTSize is set to 64x64, MinBTSize (for both width and height) is set to 4, and MaxBTDepth is set to 4. First, quadtree partitioning is 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 divided by the binary tree. Otherwise, the leaf quadtree node will be further divided 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 partitioning is allowed. When a binary tree node has a width equal to MinBTSize (4 in this example), the binary tree node means that no further horizontal partitioning is allowed. Similarly, a binary tree node with a height equal to MinBTSize indicates that no further vertical partitioning 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.

[0115] Figure 3 is a block diagram illustrating an example video encoder 200 that may perform the techniques of this disclosure. Figure 3For purposes of explanation and should not be considered a constraint on the techniques broadly exemplified and described in this disclosure. For purposes of illustration, this disclosure describes the video encoder 200 in the context of video codec standards such as the HEVC video codec standard under development and the H.266 video codec standard. However, the techniques of this disclosure are not limited to these video codec standards and are generally applicable to video encoding and decoding.

[0116] exist Figure 3 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 or all of the video data memory 230, the mode selection unit 202, the residual generation unit 204, the transform processing unit 206, the quantization unit 208, the inverse quantization unit 210, the inverse transform processing unit 212, the reconstruction unit 214, the filter unit 216, the DPB 218, and the entropy coding unit 220 may be implemented in one or more processors or in processing circuits. In addition, the video encoder 200 may include additional or alternative processors or processing circuits to perform these and other functions.

[0117] 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-chip with other components of video encoder 200, as shown, or placed off-chip relative to those components.

[0118] In the present disclosure, references to the video data memory 230 should not be interpreted as limited to a memory inside the video encoder 200 (unless otherwise specified) or a memory outside the video encoder 200 (unless otherwise specified). Instead, references to the video data memory 230 should be understood as a reference memory that stores video data received by the video encoder 200 for encoding (e.g., video data to be encoded of a current block). Figure 1 The memory 106 can also provide temporary storage for the outputs of various units of the video encoder 200 .

[0119] Shown Figure 3 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 that causes the programmable circuit to operate in a manner defined by the instructions of the software or firmware. Fixed-function circuits can execute software instructions (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.

[0120] The video encoder 200 may include an arithmetic logic unit (ALU), an elementary function unit (EFU), a digital circuit, an analog circuit, and / or a programmable core formed by a programmable circuit. In an example where the operation of the video encoder 200 is performed using software executed by a programmable circuit, the memory 106 ( Figure 1 ) may store object code for software received and executed by the video encoder 200, or another memory within the video encoder 200 (not shown) may store such instructions.

[0121] 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.

[0122] 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.

[0123] Generally, the mode selection unit 202 coordinates multiple encoding passes to test combinations of encoding parameters and derive rate-distortion values ​​of such 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.

[0124] 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".

[0125] In general, 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 prediction 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 coded pictures stored in the DPB 218). In particular, 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 generally 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 with the lowest value generated by these calculations, indicating the reference block that most closely matches the current block.

[0126] 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 prediction 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 prediction 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 respective motion vectors and combine the retrieved data (e.g., by sample-by-sample averaging or weighted averaging).

[0127] like Figure 3 As shown, in some examples, the motion compensation unit 224 includes a surround motion compensation (WMC) unit 225. The WMC unit 225 can be configured to perform one or more example techniques described in this disclosure. The WMC unit 225 can be a logic unit within the motion compensation unit 224, or can be its own independent circuit within the motion compensation unit 224.

[0128] As an example, the mode selection unit 202 may determine whether surround motion compensation is enabled. Based on the surround motion compensation being enabled, the mode selection unit 202 may determine an offset for surround motion compensation. The WMC unit 225 may generate a prediction block for the current block using the offset for surround motion compensation. As described below, using the prediction block generated with surround motion compensation, the residual generation unit 204 may generate a residual block, and the entropy encoding unit 220 may signal information indicating the residual block.

[0129] As another example, for intra prediction or intra prediction codec, the intra prediction unit 226 can generate a prediction block based on samples adjacent to the current block. For example, for directional mode, the intra prediction unit 226 can generally mathematically combine the neighboring sample values ​​and fill these calculated values ​​along a defined direction on the current block to generate a prediction block. As another example, for DC mode, the intra prediction unit 226 can calculate the average value of the neighboring samples of the current block and generate a prediction block to include the average value obtained for each sample of the prediction block.

[0130] The mode selection unit 202 provides the prediction 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 prediction block from the mode selection unit 202. The residual generation unit 204 calculates the sample-by-sample difference between the current block and the prediction block. The resulting sample-by-sample difference defines a residual block for the current block. In some examples, the residual generation unit 204 may also use residual differential pulse code modulation (RDPCM) to determine the difference between 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.

[0131] 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 codec 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 similar for inter-frame prediction. The video encoder 200 and the video decoder 300 may also support asymmetric partitioning of PU sizes of 2N×nU, 2N×nD, nL×2N, and nR×2N for inter-frame prediction.

[0132] In an example where the mode selection unit does not further split the CU into PUs, each CU may be associated with a luma codec block and a corresponding chroma codec block. As described above, the size of a CU may refer to the size of the luma codec 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.

[0133] For other video codecs such as intra block copy mode codec, affine mode codec, and linear model (LM) mode codec, as a few examples, the mode selection unit 202 generates a prediction block for the current block being encoded via a corresponding unit associated with the codec technology. In some examples, such as palette mode codec, the mode selection unit 202 may not generate a prediction block, but instead generate syntax elements that indicate how to reconstruct the block based on the selected palette. In such a mode, the mode selection unit 202 may provide these syntax elements to the entropy coding unit 220 to encode it.

[0134] As described above, the residual generation unit 204 receives video data of a current block and a corresponding prediction 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 prediction block and the current block.

[0135] The transform processing unit 206 applies one or more transforms to the residual block to generate a block of transform coefficients (referred to herein as a "transform coefficient block"). The transform processing unit 206 can apply various transforms to the residual block to form a transform coefficient block. For example, the transform processing unit 206 can apply a discrete cosine transform (DCT), a directional transform, a Karhunen-Loeve transform (KLT), or a conceptually similar transform to the residual block. In some examples, the transform processing unit 206 can perform multiple transforms on the residual block, 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.

[0136] The quantization unit 208 may quantize the transform coefficients in the transform coefficient block to produce a quantized transform coefficient block. The quantization unit 208 may quantize the transform coefficients of the transform coefficient block according to a quantization parameter (QP) value associated with the current block. The video encoder 200 (e.g., via the mode selection unit 202) may adjust the degree of quantization applied to the transform coefficient block associated with the current block by adjusting the QP value associated with the CU. Quantization may introduce information loss, and thus, the quantized transform coefficients may have lower precision than the original transform coefficients produced by the transform processing unit 206.

[0137] 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 prediction block generated by the mode selection unit 202. For example, the reconstruction unit 214 may add samples of the reconstructed residual block to corresponding samples of the prediction block generated by the mode selection unit 202 to generate a reconstructed block.

[0138] 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 operation of filter unit 216 may be skipped.

[0139] 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 to 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 to the DPB 218. The motion estimation unit 222 and the motion compensation unit 224 can retrieve a reference picture from the DPB 218 to perform inter-frame prediction on blocks of subsequent encoded pictures, where the reference picture is formed based on the reconstructed (and potentially filtered) blocks. 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.

[0140] 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 quantized transform coefficient block from the quantization unit 208. As another example, the entropy coding unit 220 may entropy encode a prediction syntax element (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 coded 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 when the syntax element is not entropy coded.

[0141] As described above, the WMC unit 225 may be configured to generate a prediction block, and the residual generation unit 204 may generate a residual block indicating a difference between the prediction block and the current block. The entropy encoding unit 220 may signal information of the residual block indicating a difference between the prediction block and the current block.

[0142] In one or more examples, the mode selection unit 202 may cause the entropy coding unit 220 to signal a syntax element in a picture parameter set (PPS) indicating an offset for wraparound motion compensation of the current block. As an example, the mode selection unit 202 may cause the entropy coding unit 220 to signal pps_ref_wraparound_offset_minus1. As described above, pps_ref_wraparound_offset_minus1 is an example way to signal information indicating an offset for wraparound motion compensation of the current block in the PPS. However, there may be various other ways to signal information indicating the offset. For example, the mode selection unit 202 may cause the entropy coding unit 220 to signal an actual offset value, or to signal information indicating a difference between the picture width and the offset.

[0143] And, the syntax element indicating the offset for wraparound motion compensation of the current block in the PPS may be considered as the first syntax element. The mode selection unit 202 may cause the entropy encoding unit 220 to signal a second syntax element indicating whether wraparound motion compensation is enabled in the PPS (e.g., signaling pps_ref_wraparound_enabled_flag). For example, in order to signal the syntax element indicating the offset for wraparound motion compensation of the current block in the PPS, the mode selection unit 202 may cause the entropy encoding unit 220 to signal a first syntax element (e.g., pps_ref_wraparound_offset_minus1 but not limited to pps_ref_wraparound_offset_minus1) based on the second syntax element indicating that wraparound motion compensation is enabled in the PPS (e.g., pps_ref_wraparound_enabled_flag but not limited to pps_ref_wraparound_enabled_flag).

[0144] In addition, the mode selection unit 202 may cause the entropy coding unit 220 to signal a syntax element (e.g., sps_ref_wraparound_enabled_flag) in a sequence parameter set (SPS) indicating whether wraparound motion compensation is enabled. The mode selection unit 202 may cause the entropy coding unit 220 to signal the syntax element in the SPS regardless of the picture width. For example, the mode selection unit 202 may not first determine whether a specific condition based on the picture width is satisfied before signaling the syntax element in the SPS indicating whether wraparound motion compensation is enabled. For example, the mode selection unit 202 may not first determine whether ((CtbSizeY / MinCbSizeY+1)<=(max_width_in_luma_samples / MinCbSizeY-1)) is satisfied before determining whether to signal the sps_ref_wraparound_enabled_flag.

[0145] However, there may be constraints on the sps_ref_wraparound_enabled_flag. As an example, if sps_ref_wraparound_enabled_flag indicates that surround motion compensation is enabled, ((CtbSizeY / MinCbSizeY+1)<=max_width_in_luma_samples / MinCbSizeY-1)) should be true. That is, sps_ref_wraparound_enabled_flag can be present in the bitstream regardless of the picture width. However, if sps_ref_wraparound_enabled_flag is true, ((CtbSizeY / MinCbSizeY+1)<=(max_width_in_luma_samples / MinCbSizeY-1)) should be true. If ((CtbSizeY / MinCbSizeY+1)<=(max_width_in_luma_samples / MinCbSizeY-1)) is false, then sps_ref_wraparound_enabled_flag is false (e.g., wraparound motion compensation is not enabled). In other words, based on the sps_ref_wraparound_enabled_flag indicating that wraparound motion compensation is enabled, (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1), where CtbSizeY is the height of the codec tree block (maximum codec block size), MinCbSizeY indicates the minimum codec block size, and pic_width_in_luma_samples indicates the picture width of the picture including the current block. Therefore, in one or more examples, the value of the sps_ref_wraparound_enabled_flag indicating that wraparound motion compensation is enabled can be constrained based on the picture width, the minimum block size, and the maximum block size.

[0146] The video encoder 200 may output a bitstream including entropy-encoded syntax elements required to reconstruct a block of a slice or picture. In particular, the entropy encoding unit 220 may output the bitstream.

[0147] The above operations are described for blocks. Such descriptions should be understood as operations for luma codec blocks and / or chroma codec blocks. As described above, in some examples, the luma codec block and the chroma codec block are the luma and chroma components of the CU. In some examples, the luma codec block and the chroma codec block are the luma and chroma components of the PU.

[0148] In some examples, operations performed for luma codec blocks do not need to be repeated for chroma codec blocks. As an example, operations for identifying motion vectors (MVs) and reference pictures for luma codec blocks do not need to be repeated to identify MVs and reference pictures for chroma blocks. Instead, the MVs of luma codec blocks may be scaled to determine the MVs of chroma blocks, and the reference pictures may be the same. As another example, the intra prediction process may be the same for luma coding blocks and chroma coding blocks.

[0149] 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 configured to encode and decode (e.g., encode) information for determining whether a syntax element indicating whether wraparound motion compensation is enabled is present in a parameter set (e.g., pic_width_in_luma_samples in a PPS and max_width_in_luma_samples in an SPS), and to encode and decode (e.g., encode) a syntax element indicating whether wraparound motion compensation is enabled in the same parameter set (e.g., encode and decode pps_ref_wraparound_enabled_flag if pic_width_in_luma_samples in a PPS is used, or encode and decode sps_ref_wraparound_enabled_flag if max_width_in_luma_samples in an SPS is used). The video encoder 200 may also be configured to encode, into a bitstream, encoding information for determining whether a syntax element indicating whether surround motion compensation is enabled is present in a parameter set, and signaling in the bitstream the encoded syntax element indicating whether surround motion compensation is enabled in the same parameter set.

[0150] Figure 4 is a block diagram illustrating an example video decoder 300 that may perform the techniques of this disclosure. Figure 4 The techniques widely exemplified and described in this disclosure are for the purpose of explanation and not limitation. For the purpose of illustration, this disclosure describes a video decoder 300 according to the technical description of VCC and HEVC. However, the techniques of this disclosure can be performed by video codec devices configured for other video codec standards.

[0151] exist Figure 4In 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 may be implemented in one or more processors or processing circuits. In addition, the video decoder 300 may include additional or alternative processors or processing circuits to perform these and other functions.

[0152] 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 to perform 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.

[0153] 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 encoded and decoded pictures, such as temporary data representing outputs from various units of video decoder 300. Generally, DPB 314 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 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 an independent storage device. In various examples, CPB memory 320 may be placed on-chip with other components of video decoder 300, or placed off-chip relative to those components.

[0154] Additionally or alternatively, in some examples, video decoder 300 may retrieve the video from memory 120 ( Figure 1) to retrieve the encoded and decoded video data. That is, memory 120 can 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 circuit of video decoder 300, memory 120 can store instructions to be executed by video decoder 300.

[0155] Show Figure 4 Various units are shown to aid in understanding the operations performed by the video decoder 300. These units may be implemented as fixed function circuits, programmable circuits, or a combination thereof. Figure 3 , fixed-function circuits refer to circuits that provide specific functions and are preset in the 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 that causes the programmable circuit to operate in a manner defined by the instructions of the software or firmware. Fixed-function circuits can execute software instructions (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.

[0156] 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.

[0157] Entropy decoding unit 302 may receive encoded video data from the CPB and entropy decode the video data to reproduce syntax elements. Prediction processing unit 304, inverse quantization unit 306, inverse transform processing unit 308, reconstruction unit 310, and filter unit 312 may generate decoded video data based on syntax elements extracted from the bitstream.

[0158] Generally, 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 (where the block currently being reconstructed (ie, decoded) may be referred to as a "current block").

[0159] The entropy decoding unit 302 may entropy decode syntax elements defining the quantized transform coefficients of the quantized transform coefficient block and transform information such as a quantization parameter (QP) and / or a transform mode indication. The inverse quantization unit 306 may use the QP associated with the quantized transform coefficient block to determine a degree of quantization, and likewise, determine a degree of inverse quantization for the inverse quantization unit 306 to apply. The inverse quantization unit 306 may inverse quantize the quantized transform coefficients (e.g., performing a bitwise left shift operation). The inverse quantization unit 306 may thereby form a transform coefficient block including the transform coefficients.

[0160] After the inverse quantization unit 306 forms the transform coefficient block, the inverse transform processing unit 308 may apply one or more inverse transforms to the transform coefficient block to generate a residual block associated with the current block. For example, the inverse transform processing unit 308 may apply an inverse DCT, an inverse integer transform, an inverse Karhunen-Loeve transform (KLT), an inverse rotational transform, an inverse directional transform, or another inverse transform to the coefficient block.

[0161] Further, prediction processing unit 304 generates a prediction block based on the prediction information syntax element entropy decoded by entropy decoding unit 302. For example, if the prediction information syntax element indicates that the current block is inter-predicted, motion compensation unit 316 may generate the prediction block. In this case, the prediction information syntax element may indicate a reference picture in DPB 314 from which to retrieve the reference block, and a motion vector that identifies the position of the reference block in the reference picture relative to the current block in the current picture. Motion compensation unit 316 may generally generate a prediction block in the same manner as for motion compensation unit 224 ( Figure 3 ) is performed in a manner substantially similar to that described herein.

[0162] like Figure 4 As shown, in some examples, the motion compensation unit 316 includes a surround motion compensation (WMC) unit 317. The WMC unit 317 can be configured to perform one or more example techniques described in this disclosure. The WMC unit 317 can be a logic unit within the motion compensation unit 316, or can be its own independent circuit within the motion compensation unit 316.

[0163] As an example, the prediction processing unit 304 may determine whether surround motion compensation is enabled. Based on the surround motion compensation being enabled, the prediction processing unit 304 may determine an offset for surround motion compensation. The WMC unit 317 may generate a prediction block for the current block using the offset for surround motion compensation. As described below, using the prediction block generated using surround motion compensation, the reconstruction unit 310 may add the prediction block to the residual block to reconstruct the current block.

[0164] As described above, the prediction processing unit 304 can determine an offset for wraparound motion compensation. In one or more examples, the prediction processing unit 304 can parse a syntax element in a picture parameter set (PPS) that indicates an offset for wraparound motion compensation for the current block. As an example, the prediction processing unit 304 can parse pps_ref_wraparound_offset_minus1 from the PPS. As described above, pps_ref_wraparound_offset_minus1 is an example way to determine information indicating an offset for wraparound motion compensation for the current block in the PPS. However, there can be various other ways to determine the information indicating the offset. For example, the prediction processing unit 304 can parse the actual offset value, or can parse information indicating the difference between the picture width and the offset.

[0165] And, the syntax element indicating the offset for wraparound motion compensation of the current block in the PPS may be considered as the first syntax element. The prediction processing unit 304 may parse the second syntax element indicating whether wraparound motion compensation is enabled in the PPS (e.g., parse pps_ref_wraparound_enabled_flag). For example, in order to parse the syntax element indicating the offset for wraparound motion compensation of the current block in the PPS, the prediction processing unit 304 may parse the first syntax element (e.g., pps_ref_wraparound_offset_minus1 but not limited to pps_ref_wraparound_offset_minus1) based on the second syntax element indicating that wraparound motion compensation is enabled in the PPS (e.g., pps_ref_wraparound_enabled_flag but not limited to pps_ref_wraparound_enabled_flag). That is, prediction processing unit 304 may first parse pps_ref_wraparound_enabled_flag, and based on pps_ref_wraparound_enabled_flag being true, prediction processing unit 304 may parse a syntax element in the PPS indicating an offset for wraparound motion compensation of the current block (eg, pps_ref_wraparound_offset_minus1 but not limited to pps_ref_wraparound_offset_minus1).

[0166] In addition, the prediction processing unit 304 may enable parsing a syntax element (e.g., sps_ref_wraparound_enabled_flag) in a sequence parameter set (SPS) that indicates whether wraparound motion compensation is enabled. The prediction processing unit 304 may parse this syntax element in the SPS regardless of the picture width. For example, the prediction processing unit 304 may not first determine whether a specific condition based on the picture width is met before parsing the syntax element in the SPS that indicates whether wraparound motion compensation is enabled. For example, the prediction processing unit 304 may not first determine whether ((CtbSizeY / MinCbSizeY+1)<=(max_width_in_luma_samples / MinCbSizeY-1)) is met before determining whether to parse the sps_ref_wraparound_enabled_flag.

[0167] However, there may be constraints on the sps_ref_wraparound_enabled_flag. As an example, if sps_ref_wraparound_enabled_flag indicates that surround motion compensation is enabled, ((CtbSizeY / MinCbSizeY+1)<=max_width_in_luma_samples / MinCbSizeY-1)) should be true. That is, sps_ref_wraparound_enabled_flag can be present in the bitstream regardless of the picture width. However, if sps_ref_wraparound_enabled_flag is true, ((CtbSizeY / MinCbSizeY+1)<=(max_width_in_luma_samples / MinCbSizeY-1)) should be true. If ((CtbSizeY / MinCbSizeY+1)<=(max_width_in_luma_samples / MinCbSizeY-1)) is false, sps_ref_wraparound_enabled_flag is false (e.g., wraparound motion compensation is not enabled). In other words, based on sps_ref_wraparound_enabled_flag indicating that wraparound motion compensation is enabled, (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1), where CtbSizeY is the height of the codec tree block (maximum codec block size), MinCbSizeY indicates the minimum codec block size, and pic_width_in_luma_samples indicates the picture width of the picture including the current block.

[0168] As another example, if the prediction information syntax element indicates that the current block is intra-predicted, the intra-prediction unit 318 may generate a prediction block according to the intra-prediction mode indicated by the prediction information syntax element. Again, the intra-prediction unit 318 may generally generate a prediction block in the same manner as for the intra-prediction unit 226 ( Figure 3 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.

[0169] The reconstruction unit 310 may reconstruct the current block using the prediction block and the residual block. For example, the reconstruction unit 310 may add samples of the residual block to corresponding samples of the prediction block to reconstruct the current block.

[0170] 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.

[0171] The video decoder 300 may store the reconstructed blocks 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 prediction and previously decoded pictures for subsequent motion compensation. In addition, the video decoder 300 may output a decoded picture from the DPB 314 for subsequent presentation on a display such as a Figure 1 on a display device such as display device 118.

[0172] In this way, the video decoder 200 represents an example of a video decoding device, which includes a memory configured to store video data, and one or more processing units implemented in circuits, which are configured to receive information for determining whether a syntax element indicating whether surround motion compensation is enabled is present in a parameter set from a bitstream (e.g., pic_width_in_luma_samples in a PPS and max_width_in_luma_samples in an SPS), and receive a syntax element indicating whether surround motion compensation is enabled in the same parameter set from the bitstream (e.g., pps_ref_wraparound_enabled_flag if pic_width_in_luma_samples in a PPS is used, or sps_ref_wraparound_enabled_flag if max_width_in_luma_samples in an SPS is used). The video decoder 300 may be configured to encode (e.g., decode) the information for determining whether a syntax element indicating whether surround motion compensation is enabled is present in a parameter set, and encode (e.g., decode) the syntax element indicating whether surround motion compensation is enabled in the same parameter set.

[0173] Figure 5 2 is a flowchart illustrating an example method for encoding a current block. The current block may include a current CU. Although the video encoder 200 ( Figure 1 and Figure 3 ), but it should be understood that other devices may be configured to perform similar Figure 5 method.

[0174] Figure 5 The examples are described with respect to processing circuitry, such as the processing circuitry of video encoder 200. Figure 5In an example of , the memory may be configured to store syntax elements of a picture parameter set (PPS). Examples of memory include memory 106, video data memory 230, DPB 218, or any other memory coupled to video encoder 200.

[0175] The processing circuitry of the video encoder 200 may be configured to inter-predictively encode a current block of video data based on the offset for surround motion compensation (500). For example, the WMC unit 225 may be configured to generate a prediction block based on the offset for surround motion compensation, and the entropy encoding unit 220 may signal information of a residual block indicating a difference between the prediction block and the current block. The residual generation unit 204 may generate a residual block indicating a difference between the prediction block and the current block.

[0176] The processing circuitry of video encoder 200 may signal a syntax element in a picture parameter set (PPS) indicating an offset for wraparound motion compensation of a current block (502). One example of a syntax element is pps_ref_wraparound_offset_minus1. However, other examples of syntax elements indicating an offset for wraparound motion compensation are possible.

[0177] In one or more examples, the processing circuitry of the video encoder 200 may signal a syntax element (e.g., pps_ref_wraparound_enabled_flag) in the PPS indicating whether wraparound motion compensation is enabled. For example, to signal a syntax element in the PPS indicating an offset for wraparound motion compensation of a current block, the processing circuitry of the video encoder 200 may be configured to signal the first syntax element (e.g., pps_ref_wraparound_offset_minus1) based on a second syntax element (e.g., pps_ref_wraparound_enabled_flag) in the PPS indicating that wraparound motion compensation is enabled.

[0178] In addition, the processing circuit of the video encoder 200 may signal a syntax element indicating whether wraparound motion compensation is enabled in a sequence parameter set (SPS) regardless of the picture width (e.g., signaling sps_ref_wraparound_enabled_flag regardless of the picture width). However, based on the sps_ref_wraparound_enabled_flag indicating that wraparound motion compensation is enabled, (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1), where CtbSizeY is the height of the coding tree block (maximum coding block size), MinCbSizeY indicates the minimum coding block size, and pic_width_in_luma_samples indicates the picture width of the picture including the current block.

[0179] Figure 6 is a flowchart illustrating an example method for decoding a current block of video data. The current block may include a current CU. Although the video decoder 300 ( Figure 1 and Figure 4 ), but it should be understood that other devices may be configured to perform similar Figure 6 method.

[0180] Figure 6 The examples are described with respect to processing circuitry, such as the processing circuitry of video decoder 300. Figure 6 In an example of , the memory may be configured to store syntax elements of a picture parameter set (PPS). Examples of memory include memory 120, CPB memory 320, DPB 314, or any other memory coupled to video decoder 300.

[0181] The processing circuitry of the video decoder 300 may be configured to parse a picture parameter set (PPS) for a syntax element indicating an offset for wraparound motion compensation of a current block of video data (600). One example of a syntax element is pps_ref_wraparound_offset_minus1. However, other examples of syntax elements indicating an offset for wraparound motion compensation are possible.

[0182] In one or more examples, the processing circuitry of the video decoder 300 may parse a syntax element in the PPS that indicates whether wraparound motion compensation is enabled (e.g., pps_ref_wraparound_enabled_flag). For example, to parse a syntax element in the PPS that indicates an offset for wraparound motion compensation of a current block, the processing circuitry of the video decoder 300 may be configured to parse the first syntax element (e.g., pps_ref_wraparound_offset_minus1) based on a second syntax element in the PPS that indicates that wraparound motion compensation is enabled (e.g., pps_ref_wraparound_enabled_flag).

[0183] In addition, the processing circuit of the video decoder 300 may parse a syntax element in a sequence parameter set (SPS) indicating whether wraparound motion compensation is enabled regardless of the picture width (e.g., parse sps_ref_wraparound_enabled_flag regardless of the picture width). However, based on the sps_ref_wraparound_enabled_flag indicating that wraparound motion compensation is enabled, (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1), where CtbSizeY is the height of the codec tree block (maximum codec block size), MinCbSizeY indicates the minimum codec block size, and pic_width_in_luma_samples indicates the picture width of the picture including the current block.

[0184] The processing circuit of the video decoder 300 may be configured to perform inter-frame prediction decoding (602) on a current block of video data based on the offset for surround motion compensation. For example, the WMC unit 317 may be configured to generate a prediction block based on the offset for surround motion compensation, and the reconstruction unit 310 may add the prediction block to the residual block to reconstruct the current block.

[0185] The following describes one or more examples that may be performed alone or in combination with one or more of the example techniques described in this disclosure.

[0186] Example 1. A method for encoding and decoding video data, the method comprising: encoding and decoding information for determining whether a syntax element indicating whether surround motion compensation is enabled exists in a parameter set; and encoding and decoding a syntax element indicating whether surround motion compensation is enabled in the same parameter set.

[0187] Example 2. The method of Example 1, wherein the parameter set is a sequence parameter set (SPS).

[0188] Example 3. The method of Example 1, wherein the parameter set is a picture parameter set (PPS).

[0189] Example 4. The method of any one of Examples 1 and 2, wherein the information used to determine whether to apply surround motion compensation includes information indicating a maximum width in terms of a number of luma samples.

[0190] Example 5. The method of any one of Examples 1 and 3, wherein the information used to determine whether to apply surround motion compensation includes information indicating a picture width in terms of a number of luma samples.

[0191] Example 6. The method of any one of Examples 1-5, further comprising: receiving information from a bitstream for determining whether a syntax element indicating whether surround motion compensation is enabled is present in a parameter set, and receiving a syntax element from the bitstream indicating whether surround motion compensation is enabled in the same parameter set, wherein encoding and decoding the information includes decoding the information, and wherein encoding and decoding the syntax element includes decoding the syntax element.

[0192] Example 7. A method of any one of Examples 1-5, wherein encoding and decoding information includes encoding the information, and encoding and decoding a syntax element includes encoding the syntax element, the method further comprising signaling in a bitstream whether the encoded information for determining whether a syntax element indicating whether surround motion compensation is enabled is present in a parameter set, and signaling in the bitstream the encoded syntax element indicating whether surround motion compensation is enabled in the same parameter set.

[0193] Example 8. A method of encoding and decoding video data, the method comprising encoding and decoding a syntax element indicating whether surround motion compensation is enabled regardless of a picture width in terms of a number of luma samples.

[0194] Example 9. The method of Example 8 further includes receiving a syntax element from a bitstream, wherein encoding and decoding the syntax element includes decoding the syntax element.

[0195] Example 10. The method of Example 8, wherein encoding and decoding the syntax element includes encoding the syntax element, and the method further includes signaling the encoded syntax element.

[0196] Example 11. A method of encoding and decoding video data, the method comprising encoding and decoding information for deriving a consistency window using any or a combination of techniques described in this disclosure.

[0197] Example 12. The method of Example 11, further comprising receiving information from a bitstream, wherein encoding and decoding the information comprises decoding the information.

[0198] Example 13. The method of Example 11, wherein encoding and decoding the information includes encoding the information, and the method further includes signaling the encoded information in a bitstream.

[0199] Example 14. A device for encoding and decoding video data, the device comprising a memory configured to store video data and a video codec, the video codec comprising at least one of fixed-function or programmable circuits, wherein the video codec is configured to perform the method of any one of Examples 1-Example 13.

[0200] Example 15. The device of Example 14, wherein the video codec comprises a video decoder, wherein the video decoder is configured to perform the method of any one of Examples 1-6, 8, 9, 11, and 12.

[0201] Example 16. The device of Example 14, wherein the video codec comprises a video encoder, wherein the video encoder is configured to perform the method of any one of Examples 1-5, 7, 8, 10, 11, and 13.

[0202] Example 17. The device of any of Examples 14-16, further comprising one or more of a display, a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box configured to display the decoded video data.

[0203] Example 18. A computer-readable storage medium having instructions stored thereon that, when executed, cause one or more processors to perform the method of any one of Examples 1-13.

[0204] Example 19. An apparatus for encoding and decoding video data, the apparatus comprising means for performing the method of any one of Examples 1-13.

[0205] It should be appreciated that, according to examples, certain actions or events of any technology described herein may be performed in a different sequence, may be added, merged, or omitted together (e.g., not all described actions or events are necessary for the practice of the technology). In addition, in some examples, actions or events may be processed concurrently rather than sequentially, such as by multithreading, interrupt processing, or multiple processors.

[0206] In one or more examples, the described functions may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted through a computer-readable medium as one or more instructions or codes and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media, which corresponds to tangible media such as data storage media, or communication media, including, for example, any media that facilitates the transfer of a computer program from one place to another according to a communication protocol. In this manner, computer-readable media may generally correspond to (1) a non-temporary 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.

[0207] As an example and not limitation, such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage devices, flash memory or any other medium that can be used to store the required program code in the form of instructions or data structures and can be accessed by a computer. Moreover, any connection is appropriately referred to as a computer-readable medium. For example, if instructions are sent from a website, server or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) or wireless technology (such as infrared, radio and microwave), the definition of the medium includes coaxial cable, fiber optic cable, twisted pair, DSL or wireless technology such as infrared, radio and microwave. However, it should be understood that computer-readable storage media and data storage media do not include connections, carriers, signals or other temporary media, but are directed to non-temporary tangible storage media. Disks and optical disks as used in this application include compact discs (CDs), laser optical disks, optical optical disks, digital versatile discs (DVDs), floppy disks and blue-ray discs, wherein disks typically reproduce data magnetically, while optical disks reproduce data optically with lasers. The above combination should also be included in the scope of computer-readable media.

[0208] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Therefore, the terms "processor" and "processing circuit" as used in this application may refer to any of the aforementioned structures or any other structures suitable for implementing the techniques described in this application. In addition, in some aspects, the functions described in this application may be provided within dedicated hardware and / or software modules configured for encoding and decoding, or incorporated in a combined codec. Similarly, the technology may be fully implemented in one or more circuits or logic elements.

[0209] 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 devices configured to perform the disclosed techniques, but do not necessarily need to be implemented by different hardware units. Rather, as described above, the various units may be combined in a codec hardware unit, or provided by a collection of interoperable hardware units, including one or more processors as described above in combination with appropriate software and / or firmware.

[0210] 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: Parsing a first syntax element in a picture parameter set PPS, the first syntax element indicating whether surround motion compensation is enabled for a current block of the video data, wherein, based on the first syntax element indicating that surround motion compensation is enabled, (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1), wherein CtbSizeY is the height of a codec tree block, MinCbSizeY indicates a minimum codec block size, and pic_width_in_luma_samples indicates a picture width of a picture including the current block; Parsing a second syntax element in a sequence parameter set SPS regardless of picture width, the second syntax element indicating whether surround motion compensation is enabled; and Based on the first syntax element and the second syntax element, inter-frame prediction decoding is performed on the current block.

2. The method according to claim 1, further comprising: Based on the first syntax element and the second syntax element indicating enabling of surround motion compensation, a third syntax element in the PPS is parsed, the third syntax element indicating an offset for surround motion compensation of the current block.

3. The method according to claim 1, wherein: The value of the second syntax element indicating enabling of surround motion compensation is further constrained based on the picture width, minimum block size, and maximum block size.

4. The method according to claim 1, wherein: Based on the second syntax element indicating that surround motion compensation is enabled, (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1).

5. The method according to claim 2, wherein: Inter-frame prediction decoding includes: generating a prediction block based on the offset for surround motion compensation; and The prediction block is added to the residual block to reconstruct the current block.

6. A device for decoding video data, the device comprising: A memory configured to store syntax elements of a picture parameter set PPS and a sequence parameter set SPS; as well as The processing circuit is configured to: Parsing a first syntax element in the PPS, the first syntax element indicating whether surround motion compensation is enabled for a current block of the video data, wherein, based on the first syntax element indicating that surround motion compensation is enabled, (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1), wherein CtbSizeY is the height of a codec tree block, and MinCbSizeY indicates a minimum codec block size, pic_width_in_luma_samples indicates the picture width of the picture including the current block; parsing a second syntax element in the SPS regardless of picture width, the second syntax element indicating whether surround motion compensation is enabled; and Based on the first syntax element and the second syntax element, inter-frame prediction decoding is performed on the current block.

7. The device according to claim 6, wherein: The processing circuit is configured to: Based on the first syntax element and the second syntax element indicating enabling of surround motion compensation, a third syntax element in the PPS is parsed, the third syntax element indicating an offset for surround motion compensation of the current block.

8. The device according to claim 6, wherein: The value of the second syntax element indicating enabling of surround motion compensation is further constrained based on the picture width, minimum block size, and maximum block size.

9. The device according to claim 6, wherein: Based on the second syntax element indicating that surround motion compensation is enabled, (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1).

10. The apparatus according to claim 7, wherein for inter-frame prediction decoding, the processing circuit is configured to: generating a prediction block based on the offset for surround motion compensation; and The prediction block is added to the residual block to reconstruct the current block. 11 . The apparatus of claim 6 , further comprising a display configured to display a picture including the current block.

12. The device of claim 6, further comprising at least one of a camera, a computer, and a wireless communication device set-top box.

13. A method for encoding video data, the method comprising: signaling a first syntax element in a picture parameter set (PPS), the first syntax element indicating whether surround motion compensation is enabled for a current block of the video data, wherein, based on the first syntax element indicating that surround motion compensation is enabled, (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1), wherein CtbSizeY is a height of a codec tree block, MinCbSizeY indicates a minimum codec block size, and pic_width_in_luma_samples indicates a picture width of a picture including the current block; signaling a second syntax element in a sequence parameter set (SPS) regardless of picture width, the second syntax element indicating whether surround motion compensation is enabled; Inter-frame prediction encoding the current block of the video data based on the offset for surround motion compensation; and Based on the first syntax element and the second syntax element indicating enabling of surround motion compensation, a third syntax element is signaled in the PPS, the third syntax element indicating the offset used for surround motion compensation of the current block.

14. The method according to claim 13, wherein: The value of the second syntax element indicating enabling of surround motion compensation is further constrained based on the picture width, minimum block size, and maximum block size.

15. The method according to claim 13, wherein: Based on the second syntax element indicating that surround motion compensation is enabled, (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1).

16. The method according to claim 13, wherein: Inter-frame prediction coding includes: generating a prediction block based on the offset for surround motion compensation; and Information of a residual block indicating a difference between the prediction block and the current block is signaled.

17. A device for encoding video data, the device comprising: A memory configured to store syntax elements of a picture parameter set PPS and a sequence parameter set SPS; as well as The processing circuit is configured to: signaling a first syntax element in the PPS, the first syntax element indicating whether surround motion compensation is enabled for a current block of the video data, wherein based on the first syntax element indicating that surround motion compensation is enabled, (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1), wherein CtbSizeY is a height of a codec tree block, and MinCbSizeY indicates a minimum codec block size, pic_width_in_luma_samples indicates the picture width of the picture including the current block; signaling a second syntax element in the SPS regardless of picture width, the second syntax element indicating whether surround motion compensation is enabled; Inter-frame prediction encoding the current block of the video data based on the offset for surround motion compensation; and Based on the first syntax element and the second syntax element indicating enabling of surround motion compensation, a third syntax element is signaled in the PPS, the third syntax element indicating the offset used for surround motion compensation of the current block.

18. The apparatus according to claim 17, wherein: The value of the second syntax element indicating enabling of surround motion compensation is further constrained based on the picture width, minimum block size, and maximum block size.

19. The apparatus according to claim 17, wherein: Based on the second syntax element indicating that surround motion compensation is enabled, (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1).

20. The apparatus of claim 17, wherein for inter-frame prediction coding, the processing circuit is configured to: generating a prediction block based on the offset for surround motion compensation; and Information of a residual block indicating a difference between the prediction block and the current block is signaled.

21. The apparatus of claim 17, further comprising a camera configured to capture a picture including the current block.

22. The device of claim 17, further comprising at least one of a camera, a computer, a wireless communication device, or a set-top box.

23. A device for decoding video data, the device comprising: means for parsing a first syntax element in a picture parameter set (PPS), the first syntax element indicating whether surround motion compensation is enabled for a current block of the video data, wherein, based on the first syntax element indicating that surround motion compensation is enabled, (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1), wherein CtbSizeY is a height of a codec tree block, MinCbSizeY indicates a minimum codec block size, and pic_width_in_luma_samples indicates a picture width of a picture including the current block; means for parsing a second syntax element in a sequence parameter set (SPS) regardless of picture width, the second syntax element indicating whether surround motion compensation is enabled; and Means for inter-prediction decoding the current block based on the first syntax element and the second syntax element.

24. A computer-readable storage medium having stored thereon instructions which, when executed, cause one or more processors to: Parsing a first syntax element in a picture parameter set PPS, the first syntax element indicating whether surround motion compensation is enabled for a current block of video data, wherein: Based on the first syntax element indicating that surround motion compensation is enabled, (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1), where CtbSizeY is the height of the codec tree block, MinCbSizeY indicates the minimum codec block size, and pic_width_in_luma_samples indicates the picture width of the picture including the current block; Parsing a second syntax element in a sequence parameter set SPS regardless of picture width, the second syntax element indicating whether surround motion compensation is enabled; and Based on the first syntax element and the second syntax element, inter-frame prediction decoding is performed on the current block.

25. A device for encoding video data, the device comprising: means for signaling, in a picture parameter set (PPS), a first syntax element indicating whether surround motion compensation is enabled for a current block of the video data, wherein, based on the first syntax element indicating that surround motion compensation is enabled, (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1), wherein CtbSizeY is a height of a codec tree block, MinCbSizeY indicates a minimum codec block size, and pic_width_in_luma_samples indicates a picture width of a picture including the current block; means for signaling a second syntax element in a sequence parameter set (SPS) regardless of picture width, the second syntax element indicating whether surround motion compensation is enabled; means for inter-prediction encoding the current block of the video data based on an offset for surround motion compensation; and means for signaling a third syntax element in the PPS based on the first syntax element and the second syntax element indicating enabling of surround motion compensation, the third syntax element indicating the offset for surround motion compensation of the current block.

26. A computer-readable storage medium having stored thereon instructions which, when executed, cause one or more processors to: A first syntax element is signaled in a picture parameter set (PPS), the first syntax element indicating whether surround motion compensation is enabled for a current block of video data, wherein Based on the first syntax element indicating that surround motion compensation is enabled, (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1), where CtbSizeY is the height of the codec tree block, MinCbSizeY indicates the minimum codec block size, and pic_width_in_luma_samples indicates the picture width of the picture including the current block; signaling a second syntax element in a sequence parameter set (SPS) regardless of picture width, the second syntax element indicating whether surround motion compensation is enabled; Inter-frame prediction encoding the current block of the video data based on the offset for surround motion compensation; and Based on the first syntax element and the second syntax element indicating enabling of surround motion compensation, a third syntax element is signaled in the PPS, the third syntax element indicating the offset used for surround motion compensation of the current block.

Images