EP4356609A1

EP4356609A1 - Motion vector candidate construction for geometric partitioning mode in video coding

Info

Publication number: EP4356609A1
Application number: EP22738304.9A
Authority: EP
Inventors: Yao-Jen Chang; Han HUANG; Vadim Seregin; Marta Karczewicz
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2021-06-15
Filing date: 2022-06-10
Publication date: 2024-04-24
Also published as: BR112023025326A2; TW202306388A; WO2022266592A1; KR20240021173A

Abstract

A video coder may be configured to determine a partitioning for a block of video data using geometric partitioning mode; construct two uni-prediction motion vector candidate lists for the block of video data, and code the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists to generate a decoded block of video data.

Description

MOTION VECTOR CANDIDATE CONSTRUCTION FOR GEOMETRIC PARTITIONING MODE IN VIDEO CODING

[0001] This application claims priority to U.S. Patent Application No. 17/806,221, filed June 9, 2022 and U.S. Provisional Application No. 63/210,883, filed June 15, 2021, the entire contents of each of which are incorporated by reference herein. U.S. Patent Application No. 17/806,221, filed June 9, 2022 claims the benefit of U.S. Provisional Application No. 63/210,883, filed June 15, 2021.

TECHNICAL FIELD

[0002] This disclosure relates to video encoding and video decoding.

BACKGROUND

[0003] Digital video capabilities can be incorporated into a wide range of devices, including digital televisions, digital direct broadcast systems, wireless broadcast systems, personal digital assistants (PDAs), laptop or desktop computers, tablet computers, e-book readers, digital cameras, digital recording devices, digital media players, video gaming devices, video game consoles, cellular or satellite radio telephones, so-called “smart phones,” video teleconferencing devices, video streaming devices, and the like. Digital video devices implement video coding techniques, such as those described in the standards defined by MPEG-2, MPEG-4, ITU-T H.263, ITU-T H.264/MPEG-4, Part 10, Advanced Video Coding (AVC), ITU-T H.265/High Efficiency Video Coding (HEVC), ITU-T H.266/Versatile Video Coding (VVC), and extensions of such standards, as well as proprietary video codecs/formats such as AOMedia Video 1 (AVI) that was developed by the Alliance for Open Media. The video devices may transmit, receive, encode, decode, and/or store digital video information more efficiently by implementing such video coding techniques.

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

SUMMARY

[0005] In general, this disclosure describes techniques for encoding and decoding video data. In particular, this disclosure describes techniques for inter-prediction of blocks of video data partitioned according to a geometric partitioning mode. The techniques of this disclosure include techniques for merge candidate list construction for geometric partitioning mode, pruning of merge candidate lists for geometric partitioning mode, and/or the use of zero motion vectors in geometric partitioning mode. The techniques of this disclosure may improve the coding performance of video codecs configured to use a geometric partitioning mode, including increasing compression and/or reducing distortion in coded video data.

[0006] In one example, a method includes determining a partitioning for a block of video data using geometric partitioning mode, constructing two uni-prediction motion vector candidate lists for the block of video data, and decoding the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists.

[0007] In another example, a device includes a memory and one or more processors in communication with the memory, the one or more processors configured to determine a partitioning for a block of video data using geometric partitioning mode, construct two uni-prediction motion vector candidate lists for the block of video data, and decode the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists.

[0008] In another example, a device includes a memory and one or more processors in communication with the memory, the one or more processors configured to determine a partitioning for a block of video data using geometric partitioning mode, construct two uni-prediction motion vector candidate lists for the block of video data, and encode the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists. [0009] In another example, a device includes means for determining a partitioning for a block of video data using geometric partitioning mode, means for constructing two uni- prediction motion vector candidate lists for the block of video data, and means for decoding the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists.

[0010] In another example, a computer-readable storage medium is encoded with instractions that, when executed, cause a programmable processor to determine a partitioning for a block of video data using geometric partitioning mode, construct two uni-prediction motion vector candidate lists for the block of video data, and decode the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists.

[0011] The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description, drawings, and claims.

BRIEF DESCRIPTION OF DRAWINGS

[0012] FIG. 1 is a block diagram illustrating an example video encoding and decoding system that may perform the techniques of this disclosure.

[0013] FIG. 2 is a conceptual diagram illustrating example geometric partitions.

[0014] FIG. 3 is a table illustrating example merge indices and motion vector candidate lists for geometric partition mode.

[0015] FIG. 4 is a block diagram illustrating an example video encoder that may perform the techniques of this disclosure.

[0016] FIG. 5 is a block diagram illustrating an example video decoder that may perform the techniques of this disclosure.

[0017] FIG. 6 is a flowchart illustrating an example method for encoding a current block in accordance with the techniques of this disclosure.

[0018] FIG. 7 is a flowchart illustrating an example method for decoding a current block in accordance with the techniques of this disclosure.

[0019] FIG. 8 is a flowchart illustrating another example method for encoding a current block in accordance with the techniques of this disclosure.

[0020] FIG. 9 is a flowchart illustrating another example method for decoding a current block in accordance with the techniques of this disclosure. DETAILED DESCRIPTION

[0021] In general, this disclosure describes techniques for encoding and decoding video data. In particular, this disclosure describes techniques for inter-prediction of blocks of video data partitioned according to a geometric partitioning mode. The techniques of this disclosure include techniques for merge candidate list construction for geometric partitioning mode, pruning of merge candidate lists for geometric partitioning mode, and/or the use of zero motion vectors in geometric partitioning mode. The techniques of this disclosure may improve the coding performance of video codecs configured to use a geometric partitioning mode, including increasing compression and/or reducing distortion in coded video data.

[0022] FIG. 1 is a block diagram illustrating an example video encoding and decoding system 100 that may perform the techniques of this disclosure. The techniques of this disclosure are generally directed to coding (encoding and/or decoding) video data. In general, video data includes any data for processing a video. Thus, video data may include raw, unencoded video, encoded video, decoded (e.g., reconstructed) video, and video metadata, such as signaling data.

[0023] As shown in FIG. 1, system 100 includes a source device 102 that provides encoded video data to be decoded and displayed by a destination device 116, in this example. In particular, source device 102 provides the video data to destination device 116 via a computer-readable medium 110. Source device 102 and destination device 116 may comprise any of a wide range of devices, including desktop computers, notebook (i.e., laptop) computers, mobile devices, tablet computers, set-top boxes, telephone handsets such as smartphones, televisions, cameras, display devices, digital media players, video gaming consoles, video streaming device, broadcast receiver devices, or the like. In some cases, source device 102 and destination device 116 may be equipped for wireless communication, and thus may be referred to as wireless communication devices.

[0024] In the example of FIG. 1, source device 102 includes video source 104, memory 106, video encoder 200, and output interface 108. Destination device 116 includes input interface 122, video decoder 300, memory 120, and display device 118. In accordance with this disclosure, video encoder 200 of source device 102 and video decoder 300 of destination device 116 may be configured to apply the techniques for merge candidate list construction for geometric partitioning mode. Thus, source device 102 represents an example of a video encoding device, while destination device 116 represents an example of a video decoding device. In other examples, a source device and a destination device may include other components or arrangements. For example, source device 102 may receive video data from an external video source, such as an external camera. Likewise, destination device 116 may interface with an external display device, rather than include an integrated display device.

[0025] System 100 as shown in FIG. 1 is merely one example. In general, any digital video encoding and/or decoding device may periform techniques for merge candidate list construction for geometric partitioning mode. Source device 102 and destination device 116 are merely examples of such coding devices in which source device 102 generates coded video data for transmission to destination device 116. This disclosure refers to a “coding” device as a device that performs coding (encoding and/or decoding) of data. Thus, video encoder 200 and video decoder 300 represent examples of coding devices, in particular, a video encoder and a video decoder, respectively. In some examples, source device 102 and destination device 116 may operate in a substantially symmetrical manner such that each of source device 102 and destination device 116 includes video encoding and decoding components. Hence, system 100 may support one-way or two-way video transmission between source device 102 and destination device 116, e.g., for video streaming, video playback, video broadcasting, or video telephony.

[0026] In general, video source 104 represents a source of video data (i.e., raw, unencoded video data) and provides a sequential series of pictures (also referred to as “flames”) of the video data to video encoder 200, which encodes data for the pictures. Video source 104 of source device 102 may include a video capture device, such as a video camera, a video archive containing previously captured raw video, and/or a video feed interface to receive video from a video content provider. As a further alternative, video source 104 may generate computer graphics-based data as the source video, or a combination of live video, archived video, and computer-generated video. In each case, video encoder 200 encodes the captured, pre-captured, or computer-generated video data. Video encoder 200 may rearrange the pictures from the received order (sometimes referred to as “display order”) into a coding order for coding. Video encoder 200 may generate a bitstream including encoded video data. Source device 102 may then output the encoded video data via output interface 108 onto computer-readable medium 110 for reception and/or retrieval by, e.g., input interface 122 of destination device 116.

[0027] Memory 106 of source device 102 and memory 120 of destination device 116 represent general purpose memories. In some examples, memories 106, 120 may store raw video data, e.g., raw video from video source 104 and raw, decoded video data from video decoder 300. Additionally or alternatively, memories 106, 120 may store software instructions executable by, e.g., video encoder 200 and video decoder 300, respectively. Although memory 106 and memory 120 are shown separately from video encoder 200 and video decoder 300 in this example, it should be understood that video encoder 200 and video decoder 300 may also include internal memories for functionally similar or equivalent purposes. Furthermore, memories 106, 120 may store encoded video data, e.g., output from video encoder 200 and input to video decoder 300. In some examples, portions of memories 106, 120 may be allocated as one or more video buffers, e.g., to store raw, decoded, and/or encoded video data.

[0028] Computer-readable medium 110 may represent any type of medium or device capable of transporting the encoded video data from source device 102 to destination device 116. In one example, computer-readable medium 110 represents a communication medium to enable source device 102 to transmit encoded video data directly to destination device 116 in real-time, e.g., via a radio frequency network or computer-based network. Output interface 108 may modulate a transmission signal including the encoded video data, and input interface 122 may demodulate the received transmission signal, according to a communication standard, such as a wireless communication protocol. The communication medium may comprise any wireless or wired communication medium, such as a radio frequency (RF) spectrum or one or more physical transmission lines. The communication medium may form part of a packet- based network, such as a local area network, a wide-area network, or a global network such as the Internet. The communication medium may include routers, switches, base stations, or any other equipment that may be usefill to facilitate communication from source device 102 to destination device 116.

[0029] In some examples, source device 102 may output encoded data from output interface 108 to storage device 112. Similarly, destination device 116 may access encoded data from storage device 112 via input interface 122. Storage device 112 may include any of a variety of distributed or locally accessed data storage media such as a hard drive, Blu-ray discs, DVDs, CD-ROMs, flash memory, volatile or non-volatile memory, or any other suitable digital storage media for storing encoded video data. [0030] In some examples, source device 102 may output encoded video data to file server 114 or another intermediate storage device that may store the encoded video data generated by source device 102. Destination device 116 may access stored video data fiom file server 114 via streaming or download.

[0031] File server 114 may be any type of server device capable of storing encoded video data and transmitting that encoded video data to the destination device 116. 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 File Transfer Protocol (FTP) or File Delivery over Unidirectional Transport (FLUTE) protocol), a content deliver}' 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. File server 114 may, additionally or alternatively, implement one or more HTTP streaming protocols, such as Dynamic Adaptive Streaming over HTTP (DASH), HTTP Live Streaming (HLS), Real Time Streaming Protocol (RTSP), HTTP Dynamic Streaming, or the like.

[0032] Destination device 116 may access encoded video data fiom 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., digital subscriber line (DSL), cable modem, etc.), or a combination of both that is 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 fiom file server 114, or other such protocols for retrieving media data.

[0033] Output interface 108 and input interface 122 may represent wireless transmitters/receivers, modems, wired networking components (e.g., Ethernet cards), wireless communication components that operate according to any of a variety of IEEE 802.11 standards, or other physical components. In examples where output interface 108 and input interfece 122 comprise wireless components, output interface 108 and input interfece 122 may be configured to transfer data, such as encoded video data, according to a cellular communication standard, such as 4G, 4G-LTE (Long-Term Evolution), LTE Advanced, 5G, or the like. In some examples where output interfece 108 comprises a wireless transmitter, output interface 108 and input interfece 122 may be configured to transfer data, such as encoded video data, according to other wireless standards, such as an IEEE 802.11 specification, an IEEE 802.15 specification (e.g., ZigBee™), a Bluetooth™ standard, or the like. In some examples, source device 102 and/or destination device 116 may include respective system-on-a-chip (SoC) devices. For example, source device 102 may include an SoC device to perform the functionality attributed to video encoder 200 and/or output interface 108, and destination device 116 may include an SoC device to perform the functionality attributed to video decoder 300 and/or input interface 122.

[0034] The techniques of this disclosure may be applied to video coding in support of any of a variety of multimedia applications, such as over-the-air television broadcasts, cable television transmissions, satellite television transmissions, Internet streaming video transmissions, such as dynamic adaptive streaming over HTTP (DASH), digital video that is encoded onto a data storage medium, decoding of digital video stored on a data storage medium, or other applications.

[0035] Input interface 122 of destination device 116 receives an encoded video bitstream from computer-readable medium 110 (e.g., a communication medium, storage device 112, file server 114, or the like). The encoded video bitstream may include signaling information defined by video encoder 200, which is also used by video decoder 300, such as syntax elements having values that describe characteristics and/or processing of video blocks or other coded units (e.g., slices, pictures, groups of pictures, sequences, or the like). Display device 118 displays decoded pictures of the decoded video data to a user. Display device 118 may represent any of a variety of display devices such as a liquid crystal display (LCD), a plasma display, an organic light emitting diode (OLED) display, or another type of display device.

[0036] Although not shown in FIG. 1, in some examples, video encoder 200 and video decoder 300 may each be integrated with an audio encoder and/or audio decoder, and may include appropriate MUX-DEMUX units, or other hardware and/or software, to handle multiplexed streams including both audio and video in a common data stream. [0037] Video encoder 200 and video decoder 300 each may be implemented as any of a variety of suitable encoder and/or decoder circuitry, such as one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), discrete logic, software, hardware, firmware or any combinations thereof. When the techniques are implemented partially in software, a device may store instructions for the software in a suitable, non- transitory computer-readable medium and execute the instructions in hardware using one or more processors to perform the techniques of this disclosure. Each of video encoder 200 and video decoder 300 may be included in one or more encoders or decoders, either of which may be integrated as part of a combined encoder/decoder (CODEC) in a respective device. A device including video encoder 200 and/or video decoder 300 may comprise an integrated circuit, a microprocessor, and/or a wireless communication device, such as a cellular telephone.

[0038] Video encoder 200 and video decoder 300 may operate according to a video coding standard, such as ITU-T H.265, also referred to as High Efficiency Video Coding (HEVC) or extensions thereto, such as the multi-view and/or scalable video coding extensions. Alternatively, video encoder 200 and video decoder 300 may operate according to other proprietary or industry standards, such as ITU-T H.266, also referred to as Versatile Video Coding (VVC). In other examples, video encoder 200 and video decoder 300 may operate according to a proprietary video codec/format, such as AOMedia Video 1 (AVI), extensions of AVI, and/or successor versions of AVI (e.g., AV2). In other examples, video encoder 200 and video decoder 300 may operate according to other proprietary formats or industry standards. The techniques of this disclosure, however, are not limited to any particular coding standard or format. In general, video encoder 200 and video decoder 300 may be configured to perform the techniques of this disclosure in conjunction with any video coding techniques that use a geometric partitioning mode.

[0039] In general, video encoder 200 and video decoder 300 may perform block-based coding of pictures. The term “block” generally refers to a structure including data to be processed (e.g., encoded, decoded, or otherwise used in the encoding and/or decoding process). For example, a block may include a two-dimensional matrix of samples of luminance and/or chrominance data. In general, video encoder 200 and video decoder 300 may code video data represented in a YUV (e.g., Y, Cb, Cr) format. That is, rather than coding red, green, and blue (RGB) data for samples of a picture, video encoder 200 and video decoder 300 may code luminance and chrominance components, where the chrominance components may include both red hue and blue hue chrominance components. In some examples, video encoder 200 converts received RGB formatted data to a YUV representation prior to encoding, and video decoder 300 converts the YUV representation to the RGB format. Alternatively, pre- and post-processing units (not shown) may perform these conversions. [0040] This disclosure may generally refer to coding (e.g., encoding and decoding) of pictures to include the process of encoding or decoding data of the picture. Similarly, this disclosure may refer to coding of blocks of a picture to include the process of encoding or decoding data for the blocks, e.g., prediction and/or residual coding. An encoded video bitstream generally includes a series of values for syntax elements representative of coding decisions (e.g., coding modes) and partitioning of pictures into blocks. Thus, references to coding a picture or a block should generally be understood as coding values for syntax elements forming the picture or block.

[0041] HEVC defines various blocks, including coding units (CUs), prediction units (PUs), and transform units (TUs). According to HEVC, a video coder (such as video encoder 200) partitions a coding tree unit (CTU) into CUs according to a quadtree structure. That is, the video coder partitions CTUs and CUs into four equal, non- overlapping squares, and each node of the quadtree has either zero or four child nodes. Nodes without child nodes may be referred to as “leaf nodes,” and CUs of such leaf nodes may include one or more PUs and/or one or more TUs. The video coder may further partition PUs and TUs. For example, in HEVC, a residual quadtree (RQT) represents partitioning of TUs. In HEVC, PUs represent inter-prediction data, while TUs represent residual data. CUs that are intra-predicted include intra-prediction information, such as an intra-mode indication.

[0042] As another example, video encoder 200 and video decoder 300 may be configured to operate according to VVC. According to VVC, a video coder (such as video encoder 200) partitions a picture into a plurality of coding tree units (CTUs). Video encoder 200 may partition a CTU according to a tree structure, such as a quadtree-binary tree (QTBT) structure or Multi-Type Tree ( MTT) structure. The QTBT structure removes the concepts of multiple partition types, such as the separation between CUs, PUs, and TUs of HEVC. A QTBT structure includes two levels: a first level partitioned according to quadtree partitioning, and a second level partitioned according to binary tree partitioning. A root node of the QTBT structure corresponds to a CTU. Leaf nodes of the binary trees correspond to coding units (CUs).

[0043] In an MTT partitioning structure, blocks may be partitioned using a quadtree (QT) partition, a binary tree (BT) partition, and one or more types of triple tree (TT) (also called ternary tree (IT)) partitions. A triple or ternary tree partition is a partition where a block is split into three sub-blocks. In some examples, a triple or ternary tree partition divides a block into three sub-blocks without dividing the original block through the center. The partitioning types in MTT (e.g., QT, BT, and TT), may be symmetrical or asymmetrical.

[0044] When operating according to the AVI codec, video encoder 200 and video decoder 300 may be configured to code video data in blocks. In AVI, the largest coding block that can be processed is called a superblock. In AVI, a superblock can be either 128x128 luma samples or 64x64 luma samples. However, in successor video coding formats (e.g., AV2), a superblock may be defined by different (e.g., larger) luma sample sizes. In some examples, a superblock is the top level of a block quadtree. Video encoder 200 may further partition a superblock into smaller coding blocks. Video encoder 200 may partition a superblock and other coding blocks into smaller blocks using square or non-square partitioning. Non-square blocks may include N/2xN, NxN/2, N/4xN, and NxN/4 blocks. Video encoder 200 and video decoder 300 may perform separate prediction and transform processes on each of the coding blocks.

[0045] AVI also defines a tile of video data. A tile is a rectangular array of superblocks that may be coded independently of other tiles. That is, video encoder 200 and video decoder 300 may encode and decode, respectively, coding blocks within a tile without using video data from other tiles. However, video encoder 200 and video decoder 300 may perform filtering across tile boundaries. Tiles may be uniform or non-uniform in size. Tile-based coding may enable parallel processing and/or multi-threading for encoder and decoder implementations.

[0046] In some examples, video encoder 200 and video decoder 300 may use a single QTBT or MTT structure to represent each of the luminance and chrominance components, while in other examples, video encoder 200 and video decoder 300 may use two or more QTBT or MTT structures, such as one QTBT/MTT structure for the luminance component and another QTBT/MTT structure for both chrominance components (or two QTBT/MTT structures for respective chrominance components). [0047] Video encoder 200 and video decoder 300 may be configured to use quadtree partitioning, QTBT partitioning, MTT partitioning, superblock partitioning, or other partitioning structures.

[0048] In some examples, a CTU includes a coding tree block (CTB) of luma samples, two corresponding CTBs of chroma samples of a picture that has three sample arrays, or a CTB of samples of a monochrome picture or a picture that is coded using three separate color planes and syntax structures used to code the samples. A CTB may be an NxN block of samples for some value of N such that the division of a component into CTBs is a partitioning. A component is an array or single sample from one of the three arrays (luma and two chroma) that compose a picture in 4:2:0, 4:2:2, or 4:4:4 color format or the array or a single sample of the array that compose a picture in monochrome format. In some examples, a coding block is an MxN block of samples for some values of M and N such that a division of a CTB into coding blocks is a partitioning.

[0049] The blocks (e.g., CTUs or CUs) may be grouped in various ways in a picture. As one example, a brick may refer to a rectangular region of CTU rows within a particular tile in a picture. A tile may be a rectangular region of CTUs within a particular tile column and a particular tile row in a picture. A tile column refers to a rectangular region of CTUs having a height equal to the height of the picture and a width specified by syntax elements (e.g., such as in a picture parameter set). A tile row refers to a rectangular region of CTUs having a height specified by syntax elements (e.g., such as in a picture parameter set) and a width equal to the width of the picture. [0050] In some examples, a tile may be partitioned into multiple bricks, each of which may include one or more CTU rows within the tile. A tile that is not partitioned into multiple bricks may also be referred to as a brick. However, a brick that is a true subset of a tile may not be referred to as a tile. The bricks in a picture may also be arranged in a slice. A slice may be an integer number of bricks of a picture that may be exclusively contained in a single network abstraction layer (NAL) unit. In some examples, a slice includes either a number of complete tiles or only a consecutive sequence of complete bricks of one tile.

[0051] This disclosure may use “NxN” and “N by N” interchangeably to refer to the sample dimensions of a block (such as a CU or other video block) in terms of vertical and horizontal dimensions, e.g., 16x16 samples or 16 by 16 samples. In general, a 16x16 CU will have 16 samples in a vertical direction (y = 16) and 16 samples in a horizontal direction (x = 16). Likewise, an NxN CU generally has N samples in a vertical direction and N samples in a horizontal direction, where N represents a nonnegative integer value. The samples in a CU may be arranged in rows and columns. Moreover, CUs need not necessarily have the same number of samples in the horizontal direction as in the vertical direction. For example, CUs may comprise NxM samples, where M is not necessarily equal to N.

[0052] Video encoder 200 encodes video data for CUs representing prediction and/or residual information, and other information. The prediction information indicates how the CU is to be predicted in order to form a prediction block for the CU. The residual information generally represents sample-by-sample differences between samples of the CU prior to encoding and the prediction block.

[0053] To predict a CU, video encoder 200 may generally form a prediction block for the CU through inter-prediction or intra-prediction. Inter-prediction generally refers to predicting the CU from data of a previously coded picture, whereas intra-prediction generally refers to predicting the CU from previously coded data of the same picture. To perform inter-prediction, video encoder 200 may generate the prediction block using one or more motion vectors. Video encoder 200 may generally perform a motion search to identify a reference block that closely matches the CU, e.g., in terms of differences between the CU and the reference block. Video encoder 200 may calculate a difference metric using a sum of absolute difference (SAD), sum of squared differences (SSD), mean absolute difference (MAD), mean squared differences (MSD), or other such difference calculations to determine whether a reference block closely matches the current CU. In some examples, video encoder 200 may predict the current CU using uni-directional prediction or bi-directional prediction.

[0054] Some examples of VVC also provide an affine motion compensation mode, which may be considered an inter-prediction mode. In affine motion compensation mode, video encoder 200 may determine two or more motion vectors that represent non- translational motion, such as zoom in or out, rotation, perspective motion, or other irregular motion types.

[0055] To perform intra-prediction, video encoder 200 may select an intra-prediction mode to generate the prediction block. Some examples of VV prCovide sixty-seven intra-prediction modes, including various directional modes, as well as planar mode and DC mode. In general, video encoder 200 selects an intra-prediction mode that describes neighboring samples to a current block (e.g., a block of a CU) from which to predict samples of the current block. Such samples may generally be above, above and to the left, or to the left of the current block in the same picture as the current block, assuming video encoder 200 codes CTUs and CUs in raster scan order (left to right, top to bottom).

[0056] Video encoder 200 encodes data representing the prediction mode for a current block. For example, for inter-prediction modes, video encoder 200 may encode data representing which of the various available inter-prediction modes is used, as well as motion information for the corresponding mode. For uni-directional or bi-directional inter-prediction, for example, video encoder 200 may encode motion vectors using advanced motion vector prediction (AMVP) or merge mode. Video encoder 200 may use similar modes to encode motion vectors for affine motion compensation mode. [0057] AVI includes two general techniques for encoding and decoding a coding block of video data. The two general techniques are intra prediction (e.g., intra frame prediction or spatial prediction) and inter prediction (e.g., inter frame prediction or temporal prediction). In the context of AVI, when predicting blocks of a current frame of video data using an intra prediction mode, video encoder 200 and video decoder 300 do not use video data from other frames of video data. For most intra prediction modes, video encoder 200 encodes blocks of a current frame based on the difference between sample values in the current block and predicted values generated from reference samples in the same frame. Video encoder 200 determines predicted values generated from the reference samples based on the intra prediction mode.

[0058] Following prediction, such as intra-prediction or inter-prediction of a block, video encoder 200 may calculate residual data for the block. The residual data, such as a residual block, represents sample by sample differences between the block and a prediction block for the block, formed using the corresponding prediction mode. Video encoder 200 may apply one or more transforms to the residual block, to produce transformed data in a transform domain instead of the sample domain. For example, video encoder 200 may apply a discrete cosine transform (DCT), an integer transform, a wavelet transform, or a conceptually similar transform to residual video data.

Additionally, video encoder 200 may apply a secondary transform following the first transform, such as a mode-dependent non-separable secondary transform (MDNSST), a signal dependent transform, a Karhunen-Loeve transform (KLT), or the like. Video encoder 200 produces transform coefficients following application of the one or more transforms.

[0059] As noted above, following any transforms to produce transform coefficients, video encoder 200 may perform quantization of the transform coefficients.

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

[0060] Following quantization, video encoder 200 may scan the transform coefficients, producing a one-dimensional vector from the two-dimensional matrix including the quantized transform coefficients. The scan may be designed to place higher energy (and therefore lower frequency) transform coefficients at the front of the vector and to place lower energy (and therefore higher frequency) transform coefficients at the back of the vector. In some examples, video encoder 200 may utilize a predefined scan order to scan the quantized transform coefficients to produce a serialized vector, and then entropy encode the quantized transform coefficients of the vector. In other examples, video encoder 200 may perform an adaptive scan. After scanning the quantized transform coefficients to form the one-dimensional vector, video encoder 200 may entropy encode the one-dimensional vector, e.g., according to context-adaptive binary arithmetic coding (CABAC). Video encoder 200 may also entropy encode values for syntax elements describing metadata associated with the encoded video data for use by video decoder 300 in decoding the video data.

[0061] To perform CABAC, video encoder 200 may assign a context within a context model to a symbol to be transmitted. The context may relate to, for example, whether neighboring values of the symbol are zero-valued or not. The probability determination may be based on a context assigned to the symbol.

[0062] Video encoder 200 may further generate syntax data, such as block-based syntax data, picture-based syntax data, and sequence-based syntax data, to video decoder 300, e.g., in a picture header, a block header, a slice header, or other syntax data, such as a sequence parameter set (SPS), picture parameter set (PPS), or video parameter set (VPS). Video decoder 300 may likewise decode such syntax data to determine how to decode corresponding video data.

[0063] In this manner, video encoder 200 may generate a bitstream including encoded video data, e.g., syntax elements describing partitioning of a picture into blocks (e.g., CUs) and prediction and/or residual information for the blocks. Ultimately, video decoder 300 may receive the bitstream and decode the encoded video data.

[0064] In general, video decoder 300 performs a reciprocal process to that performed by video encoder 200 to decode the encoded video data of the bitstream. For example, video decoder 300 may decode values for syntax elements of the bitstream using CABAC in a manner substantially similar to, albeit reciprocal to, the CABAC encoding process of video encoder 200. The syntax elements may define partitioning information for partitioning of a picture into CTUs, and partitioning of each CTU according to a corresponding partition structure, such as a QTBT structure, to define CUs of the CTU. The syntax elements may further define prediction and residual information for blocks (e.g., CUs) of video data.

[0065] The residual information may be represented by, for example, quantized transform coefficients. Video decoder 300 may inverse quantize and inverse transform the quantized transform coefficients of a block to reproduce a residual block for the block. Video decoder 300 uses a signaled prediction mode (intra- or inter-prediction) and related prediction information (e.g., motion information for inter-prediction) to form a prediction block for the block. Video decoder 300 may then combine the prediction block and the residual block (on a sample-by-sample basis) to reproduce the original block. Video decoder 300 may perform additional processing, such as performing a deblocking process to reduce visual artifacts along boundaries of the block.

This disclosure may generally refer to “signaling” certain information, such as syntax elements. The term “signaling” may generally refer to the communication of values for syntax elements and/or other data used to decode encoded video data. That is, video encoder 200 may signal values for syntax elements in the bitstream. In general, signaling refers to generating a value in the bitstream. As noted above, source device 102 may transport the bitstream to destination device 116 substantially in real time, or not in real time, such as might occur when storing syntax elements to storage device 112 for later retrieval by destination device 116.

[0066] The Versatile Video Coding (VVC) standard was developed by Joint Video Experts Team (JVET) of ITU-T and ISO/IEC to achieve substantial compression capability beyond the High Efficiency Video Coding (HEVC) standard for a broad range of applications. The VVC specification was finalized in July 2020 and published by both ITU-T and ISO/IEC. The VVC specification specifies normative bitstream and picture formats, high level syntax (HLS), coding unit level syntax, and the parsing and decoding process. VVC also specifies profiles/tiers/levels (PTL) restrictions, byte stream formats, a hypothetical reference decoder, and supplemental enhancement information (SEI) in the annex. The techniques of this disclosure, as will be described below, may be applied to extensions of VV,C AVI, or any future video coding standards or formats that use a geometric partitioning mode. [0067] This disclosure describes techniques for inter-prediction of blocks of video data partitioned according to a geometric partitioning mode. The techniques of this disclosure include techniques of merge candidate list construction for geometric partitioning mode, pruning of merge candidate lists for geometric partitioning mode, and/or the use of zero motion vectors in geometric partitioning mode. The techniques of this disclosure may improve the coding performance of video codecs configured to use a geometric partitioning mode, including increasing compression and/or reducing distortion in coded video data. In accordance with the techniques of this disclosure, as will be described in more detail below, video encoder 200 and/or video decoder 300 may be configured to determine a partitioning for a block of video data using geometric partitioning mode, construct two uni-prediction motion vector candidate lists for the block of video data, and code the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists.

[0068] In VVC, a geometric partitioning mode (GPM) is supported for inter prediction. Video encoder 200 may signal the use of the geometric partitioning mode using a CU- level flag. Video encoder 200 and video decoder 300 code video data using the geometric partitioning mode using a specific kind of merge mode, with other merge modes including the regular merge mode, the merge with motion vector difference (MMVD) mode, the combined inter-intra prediction (CIIP) mode, and the subblock merge mode. In total, 64 partitions are supported by the geometric partitioning mode inVVC for each possible CU size w x h = 2^m x 2ⁿ, with m, n 6 {3 ••• 6}, excluding 8x64 and 64x8.

[0069] FIG. 2 is a conceptual diagram illustrating example geometric partitions. When the geometric partitioning mode is used, video encoder 200 splits one of CUs 400 into two parts by a geometrically located straight line, as shown in FIG. 2. Video encoder 200 and video decoder 300 mathematically derive the location of the splitting line from an angle and offset parameters of a specific partition. Video encoder 200 and video decoder 300 may be configured to code each part of a geometric partition in the CU using inter-prediction using separate motion vectors for each partition. In one example, only uni-prediction is allowed for each partition. That is, each partition is associated with one motion vector and one reference index. The uni-prediction motion for each partition is derived as described below.

[0070] When operating according to VVC, video encoder 200 and video decoder 300 are configured to derive the uni-prediction candidate list for geometric partitioning mode directly from the merge candidate list constructed for regular merge mode. Denote n as the index of the uni-prediction motion in the geometric uni-prediction candidate list. The LX motion vector of the n-th merge candidate, with X equal to the parity (even or odd) of n, is used as the n-th uni-prediction motion vector for geometric partitioning mode. In this context, LX reference to the reference picture list 0 or 1 (e.g., LO and LI, where X may be 0 or 1). FIG. 3 shows a table 410 illustrating example merge indices and motion vector candidate lists for geometric partition mode. The motion vectors for geometric partitioning mode are marked with “x” in FIG. 3. In case a corresponding LX motion vector of the n-th extended merge candidate does not exist, the L(1 - X) motion vector of the same candidate is used instead as the uni-prediction motion vector for geometric partitioning mode.

[0071] If geometric partitioning mode is used for a current CU, then a geometric partition index indicating the partition mode of the geometric partition (e.g., angle and offset), and two merge indices (one for each partition) are further signalled. The number of a maximum geometric partitioning mode candidate size is signalled explicitly in an SPS and specifies a syntax binarization for geometric partitioning mode merge indices. After predicting each of part of the geometric partition, the sample values along the geometric partition edge are adjusted using blending processing with adaptive weights.

[0072] This disclosure describes the following techniques for merge motion vector candidate list construction, pruning, and zero motion vector padding for geometric partitioning mode. The techniques of this disclosure may improve coding efficiency and/or reduce distortion for pictures of video data coded using geometric partitioning mode. The techniques of the disclosure described below may be be applied individually or in any combination.

[0073] GEO MV List Construction

[0074] In one example of the disclosure, a geometric partitioning mode (GEO) motion vector (MV) candidate list construction is described. This example is described with relation to GEO MV candidate list construction, but the techniques of this example maybe useful other inter prediction modes that only use uni-prediction (e.g., only uses one reference picture list).

[0075] In this example, rather than using the merge candidate list from regular merge mode, video encoder 200 and video decoder 300 may be configured to construct two uni-prediction MV candidate lists (e.g., a first candidate list and a second candidate list) for GEO MV prediction when using geometric partitioning mode. Both candidate lists include L0 (list 0) MV candidates and LI (list 1) MV candidates. L0 MV candidates are from a first reference picture list (L0) and LI MV candidates are from a second reference picture list (LI). L0 MV candidates may have a higher priority than LI MV candidates in the first candidate list, and LI MV candidates may have a higher priority than L0 MV candidates in the second candidate list.

[0076] In this context, higher priority means that a particular MV candidate from a particular reference picture list are added first in an interleaved fashion. As such, for the first candidate list, MV candidates from both L0 and LI are interleaved, with L0 MV candidates being added first. For example, the first candidate list may include MV candidates in the following order: C-LO, C-Ll, C-LO, C-Ll ... C-LO represents an MV candidate from list LO and C-Ll represents an MV candidate from list LI . Accordingly, for the second candidate list, MV candidates from both LO and LI are interleaved, with LI MV candidates being added first. For example, the first candidate list may include MV candidates in the following order: C-Ll, C-LO, C-Ll, C-LO...

[0077] Accordingly, in one example of the disclosure, video encoder 200 and video decoder 300 may be configured to determine a partitioning for a block of video data using geometric partitioning mode, construct two uni-prediction motion vector candidate lists for the block of video data and code the block of video data using uni- prediction based on at least one of the two uni-prediction motion vector candidate lists. The two uni-prediction MV candidate lists include a first uni-prediction MV candidate list (first candidate list) and a second uni-prediction MV candidate list (second candidate list).

[0078] To construct the two uni-prediction motion vector candidate lists for the block of video data, video encoder 200 and video decoder 300 may construct a first candidate list of the two uni-prediction motion vector candidate lists, including interleaving first motion vector candidates from a first reference picture list with second motion vector candidates from a second reference picture list, and may construct a second candidate list of the two uni-prediction motion vector candidate lists, including interleaving the second motion vector candidates from the second reference picture list with the first motion vector candidates from the first reference picture list.

[0079] In this context, interleaving first motion vector candidates from the first reference picture list with second motion vector candidates from the second reference picture list comprises adding the first motion vector candidates and the second motion vector candidates to the first candidate list in an alternating fashion wherein a candidate from the first motion vector candidates is added first. Likewise, interleaving second motion vector candidates from the second reference picture list with first motion vector candidates from the first reference picture list comprises adding the second motion vector candidates and the first motion vector candidates to the second candidate list in an alternating fashion wherein a candidate from the second motion vector candidates is added first.

[0080] In one example, in the first uni-prediction MV candidate list (first candidate list), a base MV of the n-th uni-prediction motion vector for the first uni-prediction MV candidate list may be set equal to the n-th regular merge candidate (e.g., from the regular merge mode candidate list). The motion vector of the List X of the n-th base MV, with X equal to 0 or 1 , is used as the n-th uni-prediction motion vector for the first uni-prediction MV candidate list. In case a corresponding LX motion vector of the n-th base MV does not exist, the L(1 - X) motion vector of the same base MV candidate is used.

[0081] In another example, the base MV of the n-th uni-prediction motion vector in the first uni-prediction MV candidate list can be constructed from MV candidates of neighboring blocks, collocated blocks, or other blocks with a certain checking order, instead of the n-th regular merge candidate.

[0082] In the second uni-prediction MV candidate list (second candidate list), a base MV of the n-th uni-prediction motion vector for the second uni-prediction MV candidate list may be set equal to the n-th regular merge candidate. Then the motion vector of List Y of the n-th base MV, with Y equal to 1 or 0, is used as the n-th uni- prediction motion vector for the second uni-prediction MV candidate list. In case a corresponding LY motion vector of the n-th base MV does not exist, the L(1 - Y) motion vector of the same base MV candidate is used.

[0083] In the above examples, the relationship between X and Y is Y = 1 - X, where X may have values of 0 and 1.

[0084] In another example, the base MV of the n-th uni-prediction motion vector in the second uni-prediction MV candidate list can be constructed from MV candidates of neighboring blocks, collocated blocks, or other blocks with a certain checking order, instead of the n-th regular merge candidate.

[0085] Video encoder 200 and video decoder 300 may construct a final GEO MV candidate list from the first uni-prediction MV candidate list (first candidate list), the second uni-prediction MV candidate list (second candidate list), or both the first uni- prediction MV candidate list and the second uni-prediction MV candidate list. In general, video encoder 200 and video decoder 300 may use all of the MV candidates from the first candidate list first. If the predetermined size (e.g., 10 candidates) of the list is not full after adding all candidates from the first candidate list, then video encoder 200 and video decoder 300 may add MV candidates from the second candidate list until the final candidate list has reached the predetermined number of candidates. If the list is still short after adding candidates from the second candidate lists, video encoder 200 and video decoder 300 may pad candidates to the final candidate list. In some examples, the addition of MV candidates from the first candidate list and the second candidate list are subject to the pruning techniques described below.

[0086] In one example of the above, the size of the final GEO MV candidate list, the size of the first uni-prediction MV candidate list, and the size of the second uni- prediction MV candidate list are M, Ml, and M2, respectively, where M is a pre- assigned positive integer. If Ml < M, then Ml uni-prediction MV candidates in the first uni-prediction MV candidate list, and (M - Ml) uni-prediction MV candidates in the second uni-prediction MV candidate list are added into final the GEO MV candidate list, subject to pruning. Otherwise, if Ml > M, then M uni-prediction MV candidates in the first uni-prediction MV candidate list are added into the final GEO MV candidate list, and the candidates from the second uni-prediction MV candidate list are not used. [0087] Accordingly, in a further example of the disclosure, video encoder 200 and video decoder 300 may be configured to construct a final geometric partitioning mode motion vector candidate list using at least one of the two uni-prediction motion vector candidate lists, and code the block of video data using uni-prediction and the final geometric partitioning mode motion vector candidate list.

[0088] Pruning of GEO MV Candidates

[0089] In this example, video encoder 200 and video decoder 300 may be configured to apply a pruning process to remove redundant GEO MV candidates. For example, this pruning process may be applied while constructing the final GEO candidate list. Video encoder 200 and video decoder 300 may be configured to compare an MV candidate to be added to the final GEO MV candidate list to candidates already added to the final GEO MV candidate list. Based on the comparison result, the considered candidate may not be added to the final GEO MV candidate list. For example, if the considered candidate is already in the final GEO MV candidate list, the considered candidate to be added is not added. In one example, video encoder 200 and video decoder 300 compares an i-th GEO MV candidate with all of the j-th GEO MV candidates, where j could be 0, 1, ..., and i - 1, to check if the i-th GEO MV candidate can be pruned from (e.g., removed from or not added to the list) the final GEO MV candidate list.

[0090] In a specific example, if all of the following conditions are true in at least one of the j-th GEO MV candidates, video encode 200 and video decoder 300 are configured to prune the i-th GEO MV candidate from the final GEO merge candidate list:

1. If the same reference picture list (i.e., either L0 or LI) is used by the i-th GEO MV candidate and the j-th GEO MV candidate. For example, L0 is used by the i-th GEO MV candidate and the j-th GEO MV candidate. In another example, LI is used by the i-th GEO MV candidate and the j-th GEO MV candidate.

2. If the same reference picture list index is used by the i-th GEO MV candidate and the j-th GEO MV candidate. For example, the reference picture list index 0 is used by the i-th GEO MV candidate and the j-th GEO MV candidate. In another example, the reference picture list index 1 is used by the i-th GEO MV candidate and the j-th GEO MV candidate.

3. If the absolute value of a horizontal MV difference between the i-th GEO MV candidate and the j -th GEO MV candidate is no greater than a pre-defined MV difference threshold Tx, and the absolute value of a vertical MV difference between the i-th GEO MV candidate and the j-th GEO MV candidate is no greater than the pre-defined MV difference threshold Ty (both LO MVs and LI MVs are checked), where Tx and Ty could be any positive pre-assigned value, e.g. 1/4, 1/2, and 1 . Tx and Ty values may be equal.

[0091] In one example, the pruning process for a first candidate list may include removing a first candidate from the first candidate list based on the first candidate having the same reference picture list as another candidate in the first candidate list, the first candidate having the same reference picture list index as another candidate in the first candidate list, and the first candidate having a horizontal and vertical motion vector difference from another candidate in the first candidate list that is not greater than a threshold. Likewise, performing the second pruning process on the second candidate list may include removing a second candidate from the second candidate list based on the second candidate having the same reference picture list as another candidate in the first candidate list or the second candidate list, the second candidate having the same reference picture list index as another candidate in the first candidate list or the second candidate list, and the second candidate having a horizontal and vertical motion vector difference from another candidate in the first candidate list or the second candidate list that is not greater than the threshold.

[0092] If combined with techniques described above for candidate list construction, the pruning process can be applied to the first candidate list and the second candidate list independently. In one example, the pruning is done before the final GEO MV candidate list is constructed from those lists. In other words, the i-th GEO MV candidate in the first uni-prediction MV candidate list is compared with the j -th GEO MV candidates in the first uni-prediction MV candidate list, where j = 0, 1, ..., i - 1 , and the m-th GEO MV candidate in the second uni-prediction MV candidate list is compared with the n-th GEO MV candidates in the second uni-prediction MV candidate list, where n = 0, 1, ..., m - 1.

[0093] In another example, video encoder 200 and video decoder 300 may apply a pruning process to the first uni-prediction MV candidate list and the second uni- prediction MV candidate list jointly. In other words, t ih-teh GEO MV candidate in the first uni-prediction MV candidate list is compared with the j -th GEO MV candidates in the first uni-prediction MV candidate list, where j = 0, 1, ..., i - 1, and the m-th GEO MV candidate in the second uni-prediction MV candidate list is compared with the j-th GEO MV candidates in the first uni-prediction MV candidate list, where j = 0, 1, ..., Ml - 1 , and is also compared with the n-th GEO MV candidates in the second uni-prediction MV candidate list, where n = 0, 1, ..., m - 1.

[0094] In one example, the thresholds Tx and Ty may be adaptive values dependent on block sizes. In one example, Tx and Ty are equal to T1 if the number of samples in tire current coding block is greater than a pre-defined positive integer N 1. Otherwise, Tx and Ty are equal to T2 if the number of samples in the current coding block is greater than a pre-defined positive integer N2 and smaller than or equal to N1. Otherwise, Tx and Ty are equal to T3 if the number of samples in the current coding block is greater than a pre-defined positive integer N3 and smaller than or equal to N2. Otherwise, Tx and Ty are equal to T4. Note that N1 > N2 >N3.

[0095] In one example, the values of Tx and Ty may be adaptive values dependent on the modes selected in the GEO coding block. In one example, Tx and Ty are equal to T1 if template matching GEO mode is used in the current block. Otherwise, Tx and Ty are equal to T2 if MMVD GEO mode is selected. Otherwise, Tx and Ty are equal to T3 if regular GEO mode is selected. Note that T1 , T2, T3, and T4 mentioned above are positive values.

[0096] In another example for the conditions of the pruning process, a picture order count (POC) can be used to identify if the reference picture is the same for both the i-th GEO MV candidate and the j -th GEO MV candidate. Specifically, if all of the following conditions are true in at least one of the j-th GEO MV candidates, the i-th GEO MV candidate is pruned from the final GEO merge candidate list:

1. If the picture with the same POC value is referenced by the i-th GEO MV candidate and the j-th GEO MV candidate.

[0097] In another example of the disclosure, video encoder 200 and video decoder 300 may be configured to operate according to constraints applied to the pruning process to only enable the pruning for some GEO MV candidates. One example is that video encoder 200 and video decoder 300 are configured to only apply the pruning to the first P candidates in a GEO candidates list, where P is smaller than the size of the list. In another example, the pruning process is only applied to the first Q candidates that are pruned from (reduced from, or not added to) the candidate list, where Q is smaller than the size of the list.

[0098] In general, in one example, video encoder 200 and video decoder 300 may be configured to perform a pruning process on the final geometric partitioning mode motion vector candidate list. In another example, video encoder 200 and video decoder 300 may be configured to perform a pruning process on the two uni-prediction motion vector candidate lists (e.g., the first uni-prediction MV candidate list and the second uni- prediction MV candidate list).

[0099] Uni-Prediction Zero GEO MV Candidates

[0100] In this example of the disclosure, video encoder 200 and video decoder 300 are configured to pad uni-prediction MV candidates into the final GEO MV candidate list if the final GEO MV candidate list is not full, i.e., the number of candidates is smaller than M. The added uni-prediction MV candidates include interleaved list 0 MV candidates and list 1 MV candidates. The x and y components of the MV can be predefined fixed values. The reference indexes for the padded MV candidates can be predefined fixed values or loop over the available values.

[0101] One example is described as follows: Set an initial value for refListldx as -1. If the i-th candidate in the final GEO MV candidate list is empty, a zero MV with the List X and refListldx is padded, where X is set to be the parity of i, where parity = i & 1 , and refListldx is set to be (refListldx + 1).

[0102] Suppose the maximum number of reference indexes, maxNumRefldx, is set as follows: If slice is B-slice, maxNumRefldx is equal to min(the number of reference indexes in REF_PIC_LIST_0, the number of reference indexes in REF_PIC_LIST_1); Otherwise, maxNumRefldx is equal to the number of reference indexes in REF PIC LIST 0.

[0103] If refListldx is equal to maxNumRefldx - 1 after one candidate padding is finished, the value of refListldx is reset to be -1.

[0104] In general, video encoder 200 and video decoder 300 may be configured to add one or more zero motion vector candidates to the final geometric partitioning mode motion vector candidate list if a size of the final geometric partitioning mode motion vector candidate list is less than a threshold.

[0105] FIG. 4 is a block diagram illustrating an example video encoder 200 that may perform the techniques of this disclosure. FIG. 4 is provided for purposes of explanation and should not be considered limiting of the techniques as broadly exemplified and described in this disclosure. For purposes of explanation, this disclosure describes video encoder 200 according to the techniques of VVC (ITU-T H.266, under development), and HEVC (ITU-T H.265). However, the techniques of this disclosure may be performed by video encoding devices that are configured to other video coding standards and video coding formats, such as AVI and successors to the AVI video coding format.

[0106] In the example of FIG. 4, video encoder 200 includes video data memory 230, mode selection unit 202, residual generation unit 204, transform processing unit 206, quantization unit 208, inverse quantization unit 210, inverse transform processing unit 212, reconstruction unit 214, filter unit 216, decoded picture buffer (DPB) 218, and entropy encoding unit 220. Any or all of video data memory 230, mode selection unit 202, residual generation unit 204, transform processing unit 206, quantization unit 208, inverse quantization unit 210, inverse transform processing unit 212, reconstruction unit 214, filter unit 216, DPB 218, and entropy encoding unit 220 may be implemented in one or more processors or in processing circuitry. For instance, the units of video encoder 200 may be implemented as one or more circuits or logic elements as part of hardware circuitry, or as part of a processor, ASIC, or FPGA. Moreover, video encoder 200 may include additional or alternative processors or processing circuitry to perform these and other functions.

[0107] Video data memory 230 may store video data to be encoded by the components of video encoder 200. Video encoder 200 may receive the video data stored in video data memory 230 from, for example, video source 104 (FIG. 1). DPB 218 may act as a reference picture memory that stores reference video data for use in prediction of subsequent video data by video encoder 200. Video data memory 230 and DPB 218 may be formed by any of a variety of memory devices, such as dynamic random access memory (DRAM), including synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. Video data memory 230 and DPB 218 may be provided by the same memory device or separate memory devices. In various examples, video data memory 230 may be on-chip with other components of video encoder 200, as illustrated, or off-chip relative to those components.

[0108] In this disclosure, reference to video data memory 230 should not be interpreted as being limited to memory internal to video encoder 200, unless specifically described as such, or memory external to video encoder 200, unless specifically described as such. Rather, reference to video data memory 230 should be understood as reference memory that stores video data that video encoder 200 receives for encoding (e.g., video data for a current block that is to be encoded). Memory 106 of FIG. 1 may also provide temporary storage of outputs from the various units of video encoder 200.

[0109] The various units of FIG. 4 are illustrated to assist with understanding the operations performed by video encoder 200. The units may be implemented as fixed- function circuits, programmable circuits, or a combination thereof. Fixed-function circuits refer to circuits that provide particular functionality, and are preset on the operations that can be performed. Programmable circuits refer to circuits that can be programmed to perform various tasks, and provide flexible functionality in the operations that can be performed. For instance, programmable circuits may execute software or firmware that cause the programmable circuits to operate in the manner defined by instructions of the software or firmware. Fixed-function circuits may execute software instructions (e.g., to receive parameters or output parameters), but the types of operations that the fixed-function circuits perform are generally immutable. In some examples, one or more of the units may be distinct circuit blocks (fixed-function or programmable), and in some examples, one or more of the units may be integrated circuits.

[0110] Video encoder 200 may include arithmetic logic units (ALUs), elementary function units (EFUs), digital circuits, analog circuits, and/or programmable cores, formed from programmable circuits. In examples where the operations of video encoder 200 are performed using software executed by the programmable circuits, memory 106 (FIG. 1) may store the instructions (e.g., object code) of the software that video encoder 200 receives and executes, or another memory within video encoder 200 (not shown) may store such instructions.

[0111] Video data memory 230 is configured to store received video data. Video encoder 200 may retrieve a picture of the video data from video data memory 230 and provide the video data to residual generation unit 204 and mode selection unit 202. Video data in video data memory 230 may be raw video data that is to be encoded.

[0112] Mode selection unit 202 includes a motion estimation unit 222, a motion compensation unit 224, and an intra-prediction unit 226. Mode selection unit 202 may include additional functional units to perform video prediction in accordance with other prediction modes. As examples, mode selection unit 202 may include a palette unit, an intra-block copy unit (which may be part of motion estimation unit 222 and/or motion compensation unit 224), an affine unit, a linear model (LM) unit, or the like.

[0113] Mode selection unit 202 generally coordinates multiple encoding passes to test combinations of encoding parameters and resulting rate-distortion values for such combinations. The encoding parameters may include partitioning of CTUs into CUs, prediction modes for the CUs, transform types for residual data of the CUs, quantization parameters for residual data of the CUs, and so on. Mode selection unit 202 may ultimately select the combination of encoding parameters having rate-distortion values that are better than the other tested combinations.

[0114] Video encoder 200 may partition a picture retrieved from video data memory 230 into a series of CTUs, and encapsulate one or more CTUs within a slice. Mode selection unit 202 may partition a CTU of the picture in accordance with a tree structure, such as the MTT structure, QTBT structure, superblock structure, or the quad- tree structure described above. As described above, video encoder 200 may form one or more CUs from partitioning a CTU according to the tree structure. Such a CU may also be referred to generally as a “video block” or “block.”

[0115] In general, mode selection unit 202 also controls the components thereof (e.g., motion estimation unit 222, motion compensation unit 224, and intra-prediction unit 226) to generate a prediction block for a current block (e.g., a current CU, or in HEVC, the overlapping portion of a PU and a TU). For inter-prediction of a current block, motion estimation unit 222 may perform a motion search to identify one or more closely matching reference blocks in one or more reference pictures (e.g., one or more previously coded pictures stored in DPB 218). In particular, motion estimation unit 222 may calculate a value representative of how similar a potential reference block is to the current block, e.g., according to sum of absolute difference (SAD), sum of squared differences (SSD), mean absolute difference (MAD), mean squared differences (MSD), or the like. Motion estimation unit 222 may generally perform these calculations using sample-by-sample differences between the current block and the reference block being considered. Motion estimation unit 222 may identify a reference block having a lowest value resulting from these calculations, indicating a reference block that most closely matches the current block.

[0116] Motion estimation unit 222 may form one or more motion vectors (MVs) that defines the positions of the reference blocks in the reference pictures relative to the position of the current block in a current picture. Motion estimation unit 222 may then provide the motion vectors to motion compensation unit 224. For example, for uni- directional inter-prediction, motion estimation unit 222 may provide a single motion vector, whereas for bi-directional inter-prediction, motion estimation unit 222 may provide two motion vectors. Motion compensation unit 224 may then generate a prediction block using the motion vectors. For example, motion compensation unit 224 may retrieve data of the reference block using the motion vector. As another example, if the motion vector has fractional sample precision, motion compensation unit 224 may interpolate values for the prediction block according to one or more interpolation filters. Moreover, for bi-directional inter-prediction, motion compensation unit 224 may retrieve data for two reference blocks identified by respective motion vectors and combine the retrieved data, e.g., through sample-by-sample averaging or weighted averaging.

[0117] When operating according to the AVI video coding format, motion estimation unit 222 and motion compensation unit 224 may be configured to encode coding blocks of video data (e.g., both luma and chroma coding blocks) using translational motion compensation, affine motion compensation, overlapped block motion compensation (OBMC), and/or compound inter-intra prediction.

[0118] As another example, for intra-prediction, or intra-prediction coding, intra- prediction unit 226 may generate the prediction block from samples neighboring the current block. For example, for directional modes, intra-prediction unit 226 may generally mathematically combine values of neighboring samples and populate these calculated values in the defined direction across the current block to produce the prediction block. As another example, for DC mode, intra-prediction unit 226 may calculate an average of the neighboring samples to the current block and generate the prediction block to include this resulting average for each sample of the prediction block.

[0119] When operating according to the AVI video coding format, intra prediction unit 226 may be configured to encode coding blocks of video data (e.g., both luma and chroma coding blocks) using directional intra prediction, non-directional intra prediction, recursive filter intra prediction, chroma-from-luma (CFL) prediction, intra block copy (IBC), and/or color palette mode. Mode selection unit 202 may include additional functional units to perform video prediction in accordance with other prediction modes.

[0120] Mode selection unit 202 provides the prediction block to residual generation unit 204. Residual generation unit 204 receives a raw, unencoded version of the current block from video data memory 230 and the prediction block from mode selection unit 202. Residual generation unit 204 calculates sample-by-sample differences between the current block and the prediction block. The resulting sample-by-sample differences define a residual block for the current block. In some examples, residual generation unit 204 may also determine differences between sample values in the residual block to generate a residual block using residual differential pulse code modulation (RDPCM). In some examples, residual generation unit 204 may be formed using one or more subtractor circuits that perform binary subtraction.

[0121] In examples where mode selection unit 202 partitions CUs into PUs, each PU may be associated with a luma prediction unit and corresponding chroma prediction units. Video encoder 200 and video decoder 300 may support PUs having various sizes. As indicated above, the size of a CU may refer to the size of the luma coding block of the CU and the size of a PU may refer to the size of a luma prediction unit of the PU. Assuming that the size of a particular CU is 2Nx2N, video encoder 200 may support PU sizes of 2Nx2N or NxN for intra prediction, and symmetric PU sizes of 2Nx2N, 2NxN, Nx2N, NxN, or similar for inter prediction. Video encoder 200 and video decoder 300 may also support asymmetric partitioning for PU sizes of 2NxnU, 2NxnD, nLx2N, and nRx2N for inter prediction.

[0122] In examples where mode selection unit 202 does not further partition a CU into PUs, each CU may be associated with a luma coding block and corresponding chroma coding blocks. As above, the size of a CU may refer to the size of the luma coding block of the CU. The video encoder 200 and video decoder 300 may support CU sizes of 2Nx2N, 2NxN, or Nx2N.

[0123] For other video coding techniques such as an intra-block copy mode coding, an affine-mode coding, and linear model (LM) mode coding, as some examples, mode selection unit 202, via respective units associated with the coding techniques, generates a prediction block for the current block being encoded. In some examples, such as palette mode coding, mode selection unit 202 may not generate a prediction block, and instead generate syntax elements that indicate the manner in which to reconstruct the block based on a selected palette. In such modes, mode selection unit 202 may provide these syntax elements to entropy encoding unit 220 to be encoded.

[0124] As described above, residual generation unit 204 receives the video data for the current block and the corresponding prediction block. Residual generation unit 204 then generates a residual block for the current block. To generate the residual block, residual generation unit 204 calculates sample-by-sample differences between the prediction block and the current block.

[0125] 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”). Transform processing unit 206 may apply various transforms to a residual block to form the transform coefficient block. For example, transform processing unit 206 may apply a discrete cosine transform (DCT), a directional transform, a Karhunen-Loeve transform (KLT), or a conceptually similar transform to a residual block. In some examples, transform processing unit 206 may perform multiple transforms to a residual block, e.g., a primary transform and a secondary transform, such as a rotational transform. In some examples, transform processing unit 206 does not apply transforms to a residual block. [0126] When operating according to AVI, transform processing unit 206 may apply one or more transforms to the residual block to generate a block of transform coefficients (referred to herein as a “transform coefficient block”). Transform processing unit 206 may apply various transforms to a residual block to form the transform coefficient block. For example, transform processing unit 206 may apply a horizontal/vertical transform combination that may include a discrete cosine transform (DCT), an asymmetric discrete sine transform (ADST), a flipped ADST (e.g., an ADST in reverse order), and an identity transform (IDTX). When using an identity transform, the transform is skipped in one of the vertical or horizontal directions. In some examples, transform processing may be skipped.

[0127] Quantization unit 208 may quantize the transform coefficients in a transform coefficient block, to produce a quantized transform coefficient block. Quantization unit 208 may quantize transform coefficients of a transform coefficient block according to a quantization parameter (QP) value associated with the current block. Video encoder 200 (e.g., via mode selection unit 202) may adjust the degree of quantization applied to the transform coefficient blocks associated with the current block by adjusting the QP value associated with the CU. Quantization may introduce loss of information, and thus, quantized transform coefficients may have lower precision than the original transform coefficients produced by transform processing unit 206.

[0128] Inverse quantization unit 210 and inverse transform processing unit 212 may apply inverse quantization and inverse transforms to a quantized transform coefficient block, respectively, to reconstruct a residual block from the transform coefficient block. Reconstraction unit 214 may produce a reconstructed block corresponding to the current block (albeit potentially with some degree of distortion) based on the reconstructed residual block and a prediction block generated by mode selection unit 202. For example, reconstruction unit 214 may add samples of the reconstructed residual block to corresponding samples from the prediction block generated by mode selection unit 202 to produce the reconstructed block.

[0129] Filter unit 216 may perform one or more filter operations on reconstructed blocks. For example, filter unit 216 may perform deblocking operations to reduce blockiness artifacts along edges of CUs. Operations of filter unit 216 may be skipped, in some examples.

[0130] When operating according to AVI , filter unit 216 may perform one or more filter operations on reconstructed blocks. For example, filter unit 216 may perform deblocking operations to reduce blockiness artifacts along edges of CUs. In other examples, filter unit 216 may apply a constrained directional enhancement filter (CDEF), which may be applied after deblocking, and may include the application of non-separable, non-linear, low-pass directional filters based on estimated edge directions. Filter unit 216 may also include a loop restoration filter, which is applied after CDEF, and may include a separable symmetric normalized Wiener filter or a dual self-guided filter.

[0131] Video encoder 200 stores reconstructed blocks in DPB 218. For instance, in examples where operations of filter unit 216 are not performed, reconstruction unit 214 may store reconstructed blocks to DPB 218. In examples where operations of filter unit 216 are performed, filter unit 216 may store the filtered reconstructed blocks to DPB 218. Motion estimation unit 222 and motion compensation unit 224 may retrieve a reference picture from DPB 218, formed from the reconstructed (and potentially filtered) blocks, to inter-predict blocks of subsequently encoded pictures. In addition, intra-prediction unit 226 may use reconstructed blocks in DPB 218 of a current picture to intra-predict other blocks in the current picture.

[0132] In general, entropy encoding unit 220 may entropy encode syntax elements received from other functional components of video encoder 200. For example, entropy encoding unit 220 may entropy encode quantized transform coefficient blocks from quantization unit 208. As another example, entropy encoding unit 220 may entropy encode prediction syntax elements (e.g., motion information for inter-prediction or intra-mode information for intra-prediction) from mode selection unit 202. Entropy encoding unit 220 may perform one or more entropy encoding operations on the syntax elements, which are another example of video data, to generate entropy-encoded data. For example, entropy encoding unit 220 may perform a context-adaptive variable length coding (CAVLC) operation, a CABAC operation, a variable-to-variable (V2V) length coding operation, a syntax-based context-adaptive binary arithmetic coding (SBAC) operation, a Probability Interval Partitioning Entropy (PIPE) coding operation, an Exponential-Golomb encoding operation, or another type of entropy encoding operation on the data. In some examples, entropy encoding unit 220 may operate in bypass mode where syntax elements are not entropy encoded.

[0133] Video encoder 200 may output a bitstream that includes the entropy encoded syntax elements needed to reconstruct blocks of a slice or picture. In particular, entropyencoding unit 220 may output the bitstream . [0134] In accordance with AVI, entropy encoding unit 220 may be configured as a symbol-to-symbol adaptive multi-symbol arithmetic coder. A syntax element in AVI includes an alphabet of N elements, and a context (e.g., probability model) includes a set of N probabilities. Entropy encoding unit 220 may store the probabilities as n-bit (e.g., 15-bit) cumulative distribution functions (CDFs). Entropy encoding unit 22 may perform recursive scaling, with an update factor based on the alphabet size, to update the contexts.

[0135] The operations described above are described with respect to a block. Such description should be understood as being operations for a luma coding block and/or chroma coding blocks. As described above, in some examples, the luma coding block and chroma coding blocks are luma and chroma components of a CU. In some examples, the luma coding block and the chroma coding blocks are luma and chroma components of a PU.

[0136] In some examples, operations performed with respect to a luma coding block need not be repeated for the chroma coding blocks. As one example, operations to identify a motion vector (MV) and reference picture for a luma coding block need not be repeated for identifying a MV and reference picture for the chroma blocks. Rather, the MV for the luma coding block may be scaled to determine the MV for the chroma blocks, and the reference picture may be the same. As another example, the intra- prediction process may be the same for the luma coding block and the chroma coding blocks.

[0137] Video encoder 200 represents an example of a device configured to encode video data including a memory configured to store video data, and one or more processing units implemented in circuitry and configured to determine a partitioning for a block of video data using geometric partitioning mode, construct two uni-prediction motion vector candidate lists for the block of video data, and encode the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists.

[0138] FIG. 5 is a block diagram illustrating an example video decoder 300 that may perform the techniques of this disclosure. FIG. 5 is provided for purposes of explanation and is not limiting on the techniques as broadly exemplified and described in this disclosure. For purposes of explanation, this disclosure describes video decoder 300 according to the techniques of VV (CITU-T H.266, under development), and HEVC (ITU-T H.265). However, the techniques of this disclosure may be performed by video coding devices that are configured to other video coding standards.

[0139] In the example of FIG. 5, video decoder 300 includes coded picture buffer (CPB) memory 320, entropy decoding unit 302, prediction processing unit 304, inverse quantization unit 306, inverse transform processing unit 308, reconstruction unit 310, filter unit 312, and decoded picture buffer (DPB) 314. Any or all of CPB memory 320, entropy decoding unit 302, prediction processing unit 304, inverse quantization unit 306, inverse transform processing unit 308, reconstruction unit 310, filter unit 312, and DPB 314 may be implemented in one or more processors or in processing circuitry. For instance, the units of video decoder 300 may be implemented as one or more circuits or logic elements as part of hardware circuitry, or as part of a processor, ASIC, or FPGA. Moreover, video decoder 300 may include additional or alternative processors or processing circuitry to perform these and other functions.

[0140] Prediction processing unit 304 includes motion compensation unit 316 and intra- prediction unit 318. Prediction processing unit 304 may include additional units to perform prediction in accordance with other prediction modes. As examples, prediction processing unit 304 may include a palette unit, an intra-block copy unit (which may form part of motion compensation unit 316), an affine unit, a linear model (LM) unit, or the like. In other examples, video decoder 300 may include more, fewer, or different functional components.

[0141] When operating according to AVI, compensation unit 316 may be configured to decode coding blocks of video data (e.g., both luma and chroma coding blocks) using translational motion compensation, affine motion compensation, OBMC, and/or compound inter-intra prediction, as described above. Intra prediction unit 318 may be configured to decode coding blocks of video data (e.g., both luma and chroma coding blocks) using directional intra prediction, non-directional intra prediction, recursive filter intra prediction, CFL, intra block copy (IBC), and/or color palette mode, as described above.

[0142] CPB memory 320 may store video data, such as an encoded video bitstream, to be decoded by the components of video decoder 300. The video data stored in CPB memory 320 may be obtained, for example, from computer-readable medium 110 (FIG. 1). CPB memory 320 may include a CPB that stores encoded video data (e.g., syntax elements) from an encoded video bitstream. Also, CPB memory 320 may store video data other than syntax elements of a coded picture, such as temporary data representing outputs from the various units of video decoder 300. DPB 314 generally stores decoded pictures, which video decoder 300 may output and/or use 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 memory devices, such as DRAM, including SDRAM, MRAM, RRAM, or other types of memory devices. CPB memory 320 and DPB 314 may be provided by the same memory device or separate memory devices. In various examples, CPB memory 320 may be on-chip with other components of video decoder 300, or off-chip relative to those components.

[0143] Additionally or alternatively, in some examples, video decoder 300 may retrieve coded video data from memory 120 (FIG. 1). That is, memory 120 may store data as discussed above with CPB memory 320. Likewise, memory 120 may store instructions to be executed by video decoder 300, when some or all of f tuhnectionality of video decoder 300 is implemented in software to be executed by processing circuitry of video decoder 300.

[0144] The various units shown in FIG. 5 are illustrated to assist with understanding the operations performed by video decoder 300. The units may be implemented as fixed- function circuits, programmable circuits, or a combination thereof. Similar to FIG. 4, fixed-function circuits refer to circuits that provide particular functionality, and are preset on the operations that can be performed. Programmable circuits refer to circuits that can be programmed to perform various tasks, and provide flexible functionality in the operations that can be performed. For instance, programmable circuits may execute software or firmware that cause the programmable circuits to operate in the manner defined by instructions of the software or firmware. Fixed-function circuits may execute software instructions (e.g., to receive parameters or output parameters), but the types of operations that the fixed-function circuits perform are generally immutable. In some examples, one or more of the units may be distinct circuit blocks (fixed-function or programmable), and in some examples, one or more of the units may be integrated circuits.

[0145] Video decoder 300 may include ALUs, EFUs, digital circuits, analog circuits, and/or programmable cores formed from programmable circuits. In examples where the operations of video decoder 300 are performed by software executing on the programmable circuits, on-chip or off-chip memory may store instructions (e.g., object code) of the software that video decoder 300 receives and executes. [0146] 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 the syntax elements extracted from the bitstream.

[0147] In general, video decoder 300 reconstructs a picture on a block-by-block basis. Video decoder 300 may perform a reconstruction operation on each block individually (where the block currently being reconstructed, i.e., decoded, may be referred to as a “current block”).

[0148] Entropy decoding unit 302 may entropy decode syntax elements defining quantized transform coefficients of a quantized transform coefficient block, as well as transform information, such as a quantization parameter (QP) and/or transform mode indication(s). Inverse quantization unit 306 may use the QP associated with the quantized transform coefficient block to determine a degree of quantization and, likewise, a degree of inverse quantization for inverse quantization unit 306 to apply. Inverse quantization unit 306 may, for example, perform a bitwise left-shift operation to inverse quantize the quantized transform coefficients. Inverse quantization unit 306 may thereby form a transform coefficient block including transform coefficients.

[0149] After inverse quantization unit 306 forms the transform coefficient block, 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, inverse transform processing unit 308 may appfy an inverse DCT, an inverse integer transform, an inverse Karhunen-Loeve transform (KLT), an inverse rotational transform, an inverse directional transform, or another inverse transform to the transform coefficient block.

[0150] Furthermore, prediction processing unit 304 generates a prediction block according to prediction information syntax elements that were entropy decoded by entropy decoding unit 302. For example, if the prediction information syntax elements indicate that the current block is inter-predicted, motion compensation unit 316 may generate the prediction block. In this case, the prediction information syntax elements may indicate a reference picture in DPB 314 from which to retrieve a reference block, as well as a motion vector identifying a location of the reference block in the reference picture relative to the location of the current block in the current picture. Motion compensation unit 316 may generally perform the inter-prediction process in a manner that is substantially similar to that described with respect to motion compensation unit 224 (HG. 4).

[0151] As another example, if the prediction information syntax elements indicate that the current block is intra-predicted, intra-prediction unit 318 may generate the prediction block according to an intra-prediction mode indicated by the prediction information syntax elements. Again, intra-prediction unit 318 may generally perform the intra-prediction process in a manner that is substantially similar to that described with respect to intra-prediction unit 226 (FIG. 4). Intra-prediction unit 318 may retrieve data of neighboring samples to the current block from DPB 314.

[0152] Reconstruction unit 310 may reconstruct the current block using the prediction block and the residual block. For example, reconstruction unit 310 may add samples of the residual block to corresponding samples of the prediction block to reconstruct the current block.

[0153] Filter unit 312 may perform one or more filter operations on reconstructed blocks. For example, filter unit 312 may perform deblocking operations to reduce blockiness artifacts along edges of the reconstructed blocks. Operations of filter unit 312 are not necessarily performed in all examples.

[0154] Video decoder 300 may store the reconstructed blocks in DPB 314. For instance, in examples where operations of filter unit 312 are not performed, reconstraction unit 310 may store reconstructed blocks to DPB 314. In examples where operations of filter unit 312 are performed, filter unit 312 may store the filtered reconstructed blocks to DPB 314. As discussed above, DPB 314 may provide reference information, such as samples of a current picture for intra-prediction and previously decoded pictures for subsequent motion compensation, to prediction processing unit 304. Moreover, video decoder 300 may output decoded pictures (e.g., decoded video) from DPB 314 for subsequent presentation on a display device, such as display device 118 of HG. 1.

[0155] In this manner, video decoder 300 represents an example of a video decoding device including a memory configured to store video data, and one or more processing units implemented in circuitry and configured to determine a partitioning for a block of video data using geometric partitioning mode, construct two uni-prediction motion vector candidate lists for the block of video data, and decode the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists. [0156] FIG. 6 is a flowchart illustrating an example method for encoding a current block in accordance with the techniques of this disclosure. The current block may comprise a current CU. Although described with respect to video encoder 200 (FIGS. 1 and 4), it should be understood that other devices may be configured to perform a method similar to that of FIG. 6.

[0157] In this example, video encoder 200 initially predicts the current block (350). For example, video encoder 200 may form a prediction block for the current block. Video encoder 200 may then calculate a residual block for the current block (352). To calculate the residual block, video encoder 200 may calculate a difference between the original, unencoded block and the prediction block for the current block. Video encoder 200 may then transform the residual block and quantize transform coefficients of the residual block (354). Next, video encoder 200 may scan the quantized transform coefficients of the residual block (356). During the scan, or following the scan, video encoder 200 may entropy encode the transform coefficients (358). For example, video encoder 200 may encode the transform coefficients using CAVLC or CABAC. Video encoder 200 may then output the entropy encoded data of the block (360).

[0158] FIG. 7 is a flowchart illustrating an example method for decoding a current block of video data in accordance with the techniques of this disclosure. The current block may comprise a current CU. Although described with respect to video decoder 300 (FIGS. 1 and 5), it should be understood that other devices may be configured to perform a method similar to that of FIG. 7.

[0159] Video decoder 300 may receive entropy encoded data for the current block, such as entropy encoded prediction information and entropy encoded data for transform coefficients of a residual block corresponding to the current block (370). Video decoder 300 may entropy decode the entropy encoded data to determine prediction information for the current block and to reproduce transform coefficients of the residual block (372). Video decoder 300 may predict the current block (374), e.g., using an intra- or inter- prediction mode as indicated by the prediction information for the current block, to calculate a prediction block for the current block. Video decoder 300 may then inverse scan the reproduced transform coefficients (376), to create a block of quantized transform coefficients. Video decoder 300 may then inverse quantize the transform coefficients and apply an inverse transform to the transform coefficients to produce a residual block (378). Video decoder 300 may ultimately decode the current block by combining the prediction block and the residual block (380). [0160] FIG. 8 is a flowchart illustrating another example method for encoding a current block in accordance with the techniques of this disclosure. The techniques of FIG. 8 may be performed by one or more structural components of video encoder 200, including motion estimation unit 222 and/or motion compensation unit 224 (FIG. 4). [0161] In one example, video encoder 200 may be configured to determine a partitioning for the block of video data using geometric partitioning mode (800), construct two uni-prediction motion vector candidate lists for the block of video data (802), and encode the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists to generate an encoded block of video data (804).

[0162] In one example, to construct two uni-prediction motion vector candidate lists for the block of video data, video encoder 200 is further configured to construct a first candidate list of the two uni-prediction motion vector candidate lists, including interleaving first motion vector candidates from a first reference picture list with second motion vector candidates from a second reference picture list, and construct a second candidate list of the two uni-prediction motion vector candidate lists, including interleaving the second motion vector candidates fiom the second reference picture list with the first motion vector candidates fiom the first reference picture list.

[0163] In another example, video encoder 200 is configured to perform a first pruning process on the first candidate list, and perform a second pruning process on the second candidate list.

[0164] FIG. 9 is a flowchart illustrating another example method for decoding a current block in accordance with the techniques of this disclosure. The techniques of FIG. 8 may be performed by one or more structural components of video decoder 300, including motion compensation unit 316 (FIG. 5).

[0165] In one example, video decoder 300 is configured to determine a partitioning for the block of video data using geometric partitioning mode (900), construct two uni- prediction motion vector candidate lists for the block of video data (902), and decode the block of video data using uni-prediction based on at least one of the two uni- prediction motion vector candidate lists to generate a decoded block of video data (904). [0166] In one example, to construct two uni-prediction motion vector candidate lists for the block of video data, video decoder 300 is configured to construct a first candidate list of the two uni-prediction motion vector candidate lists, including interleaving first motion vector candidates from a first reference picture list with second motion vector candidates from a second reference picture list, and construct a second candidate list of the two uni-prediction motion vector candidate lists, including interleaving the second motion vector candidates from the second reference picture list with the first motion vector candidates from the first reference picture list.

[0167] In one example, to interleave first motion vector candidates from the first reference picture list with second motion vector candidates from the second reference picture list, video decoder 300 is configured to add the first motion vector candidates and the second motion vector candidates to the first candidate list in an alternating fashion wherein a candidate from the first motion vector candidates is added first.

[0168] In another example, to interleave second motion vector candidates from the second reference picture list with first motion vector candidates from the first reference picture list, video decoder 300 is configured to add the second motion vector candidates and the first motion vector candidates to the second candidate list in an alternating fashion wherein a candidate from the second motion vector candidates is added first.

[0169] In another example, video decoder 300 is configured to perform a first pruning process on the first candidate list, and perform a second pruning process on the second candidate list. To perform the first pruning process on the first candidate list, video decoder 300 may be configured to remove a first candidate from the first candidate list based on the first candidate having the same reference picture list as another candidate in the first candidate list, the first candidate having the same reference picture list index as another candidate in the first candidate list, and the first candidate having a horizontal and vertical motion vector difference from another candidate in the first candidate list that is not greater than a threshold. Likewise, to perform the second pruning process on the second candidate list, video decoder 300 is configured to remove a second candidate from the second candidate list based on the second candidate having the same reference picture list as another candidate in the first candidate list or the second candidate list, the second candidate having the same reference picture list index as another candidate in the first candidate list or the second candidate list, and the second candidate having a horizontal and vertical motion vector difference from another candidate in the first candidate list or the second candidate list that is not greater than the threshold. [0170] In another example, video decoder 300 is configured to construct a final geometric partitioning mode motion vector candidate list using the first candidate list and the second candidate list. In one example, to construct the final geometric partitioning mode motion vector candidate list using the first candidate list and the second candidate list, video decoder 300 is configured to add the first motion vector candidates from the first candidate list to the final geometric partitioning mode motion vector candidate list, add, in the case that the final geometric partitioning mode motion vector candidate list is less than a predetermined number of candidates after adding the first motion vector candidates, the second motion vector candidates from the second candidate list to the final geometric partitioning mode motion vector candidate list, and pad, in the case that the final geometric partitioning mode motion vector candidate list is less than the predetermined number of candidates after adding the first motion vector candidates and the second motion vector candidates, zero motion vector candidates to the final geometric partitioning mode motion vector candidate list. In another example, video decoder 300 is configured to perform a pruning process on the final geometric partitioning mode motion vector candidate list. To decode the block of video data using uni-prediction, video decoder 300 is configured to decode the block of video data using uni-prediction and the final geometric partitioning mode motion vector candidate list. [0171] Other illustrative aspects of the disclosure are described below.

[0172] Aspect 1A - A method of coding video data, the method comprising: determining a partitioning for a block of video data using geometric partitioning mode; constructing two uni-prediction motion vector candidate lists for the block of video data; and coding the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists.

[0173] Aspect 2A - The method of Aspect 1A, further comprising: constructing a final geometric partitioning mode motion vector candidate list using at least one of the two uni-prediction motion vector candidate lists.

[0174] Aspect 3A - The method of Aspect 2A, wherein coding the block of video data using uni-prediction comprises: coding the block of video data using uni-prediction and the final geometric partitioning mode motion vector candidate list.

[0175] Aspect 4A - The method of Aspect 3A, further comprising: performing a pruning process on the final geometric partitioning mode motion vector candidate list. [0176] Aspect 5A - The method of any of Aspects 1A-4A, further comprising: performing a pruning process on the two uni-prediction motion vector candidate lists. [0177] Aspect 6A - The method of Aspect 3 A, further comprising: adding one or more zero motion vector candidates to the final geometric partitioning mode motion vector candidate list if a size of the final geometric partitioning mode motion vector candidate list is less than a threshold. [0178] Aspect 7A - The method of any of Aspects 1A-6A, wherein coding comprises decoding.

[0179] Aspect 8A - The method of any of Aspects 1A-6A, wherein coding comprises encoding.

[0180] Aspect 9A - A device for coding video data, the device comprising one or more means for performing the method of any of Aspects 1A-8A.

[0181] Aspect 10A - The device of Aspect 9A, wherein the one or more means comprise one or more processors implemented in circuitry.

[0182] Aspect 11A - The device of any of Aspects 9A and 10A, further comprising a memory to store the video data.

[0183] Aspect 12A - The device of any of Aspects 9A-11A, further comprising a display configured to display decoded video data.

[0184] Aspect 13A - The device of any of Aspects 9A-12A, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

[0185] Aspect 14A - The device of any of Aspects 9A-13A, wherein the device comprises a video decoder.

[0186] Aspect 15A - The device of any of Aspects 9A-14A, wherein the device comprises a video encoder.

[0187] Aspect 16A - A computer-readable storage medium having stored thereon instructions that, when executed, cause one or more processors to perform the method of any of Aspects 1A-8A.

[0188] Aspect 17A - A device for coding video data, the device comprising: means for determining a partitioning for a block of video data using geometric partitioning mode; means for constructing two uni-prediction motion vector candidate lists for the block of video data; and means for coding th belock of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists.

[0189] Aspect IB - A method of decoding video data, the method comprising: determining a partitioning for a block of video data using geometric partitioning mode; constructing two uni-prediction motion vector candidate lists for the block of video data; and decoding the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists to generate a decoded block of video data. [0190] Aspect 2B - The method of Aspect IB, wherein constructing two uni-prediction motion vector candidate lists for the block of video data comprises: constructing a first candidate list of the two uni-prediction motion vector candidate lists, including interleaving first motion vector candidates from a first reference picture list with second motion vector candidates from a second reference picture list; and constructing a second candidate list of the two uni-prediction motion vector candidate lists, including interleaving the second motion vector candidates fiom the second reference picture list with the first motion vector candidates from the first reference picture list.

[0191] Aspect 3B - The method of Aspect 2B, wherein interleaving first motion vector candidates from the first reference picture list with second motion vector candidates fiom the second reference picture list comprises adding the first motion vector candidates and the second motion vector candidates to the first candidate list in an alternating fashion wherein a candidate from the first motion vector candidates is added first.

[0192] Aspect 4B - The method of Aspect 2B, wherein interleaving second motion vector candidates from the second reference picture list with first motion vector candidates from the first reference picture list comprises adding the second motion vector candidates and the first motion vector candidates to the second candidate list in an alternating fashion wherein a candidate from the second motion vector candidates is added first.

[0193] Aspect 5B - The method of Aspect 2B, further comprising: performing a first pruning process on the first candidate list; and performing a second pruning process on the second candidate list.

[0194] Aspect 6B - The method of Aspect 5B, wherein performing the first pruning process on the first candidate list comprises: removing a first candidate from the first candidate list based on the first candidate having the same reference picture list as another candidate in the first candidate list, the first candidate having the same reference picture list index as another candidate in the first candidate list, and the first candidate having a horizontal and vertical motion vector difference from another candidate in the first candidate list that is not greater than a threshold, and wherein performing the second pruning process on the second candidate list comprises: removing a second candidate from the second candidate list based on the second candidate having the same reference picture list as another candidate in the first candidate list or the second candidate list, the second candidate having the same reference picture list index as another candidate in the first candidate list or the second candidate list, and the second candidate having a horizontal and vertical motion vector difference from another candidate in the first candidate list or the second candidate list that is not greater than the threshold.

[0195] Aspect 7B - The method of Aspect 2B, further comprising: constructing a final geometric partitioning mode motion vector candidate list using the first candidate list and the second candidate list.

[0196] Aspect 8B - The method of Aspect 7B, wherein constructing the final geometric partitioning mode motion vector candidate list using the first candidate list and the second candidate list comprises: adding the first motion vector candidates from the first candidate list to the final geometric partitioning mode motion vector candidate list; adding, in the case that the final geometric partitioning mode motion vector candidate list is less than a predetermined number of candidates after adding the first motion vector candidates, the second motion vector candidates from the second candidate list to the final geometric partitioning mode motion vector candidate list; and padding, in the case that the final geometric partitioning mode motion vector candidate list is less than the predetermined number of candidates after adding the first motion vector candidates and the second motion vector candidates, zero motion vector candidates to the final geometric partitioning mode motion vector candidate list.

[0197] Aspect 9B - The method of Aspect 7B, further comprising: performing a pruning process on the final geometric partitioning mode motion vector candidate list.

[0198] Aspect 10B - The method of Aspect 7B, wherein decoding the block of video data using uni-prediction comprises: decoding the block of video data using uni- prediction and the final geometric partitioning mode motion vector candidate list.

[0199] Aspect 1 IB - The method of Aspect IB, further comprising: displaying a picture that includes the decoded block of video data.

[0200] Aspect 12B - An apparatus configured to decode video data, the apparatus comprising: a memory configured to store a block of video data; and one or more processors in communication with the memory, the one or more processors configured to: determine a partitioning for the block of video data using geometric partitioning mode; construct two uni-prediction motion vector candidate lists for the block of video data; and decode the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists to generate a decoded block of video data. [0201] Aspect 13B - The apparatus of Aspect 12B, wherein to construct two uni- prediction motion vector candidate lists for the block of video data, the one or more processors are further configured to: construct a first candidate list of the two uni- prediction motion vector candidate lists, including interleaving first motion vector candidates from a first reference picture list with second motion vector candidates from a second reference picture list; and construct a second candidate list of the two uni- prediction motion vector candidate lists, including interleaving the second motion vector candidates from the second reference picture list with the first motion vector candidates from the first reference picture list.

[0202] Aspect 14B - The apparatus of Aspect 13B, wherein to interleave first motion vector candidates from the first reference picture list with second motion vector candidates from the second reference picture list, the one or more processors are configured to add the first motion vector candidates and the second motion vector candidates to the first candidate list in an alternating fashion wherein a candidate from the first motion vector candidates is added first.

[0203] Aspect 15B - The apparatus of Aspect 13B, wherein to interleave second motion vector candidates from the second reference picture list with first motion vector candidates from the first reference picture list, the one or more processors are configured to add the second motion vector candidates and the first motion vector candidates to the second candidate list in an alternating fashion wherein a candidate from the second motion vector candidates is added first.

[0204] Aspect 16B - The apparatus of Aspect 13B, wherein the one or more processors are further configured to: perform a first pruning process on the first candidate list; and perform a second pruning process on the second candidate list.

[0205] Aspect 17B - The apparatus of Aspect 16B, wherein to perform the first pruning process on the first candidate list, the one or more processors are configured to: remove a first candidate from the first candidate list based on the first candidate having the same reference picture list as another candidate in the first candidate list, the first candidate having the same reference picture list index as another candidate in the first candidate list, and the first candidate having a horizontal and vertical motion vector difference from another candidate in the first candidate list that is not greater than a threshold, and wherein to perform the second pruning process on the second candidate list, the one or more processors are configured to: remove a second candidate from the second candidate list based on the second candidate having the same reference picture list as another candidate in the first candidate list or the second candidate list, the second candidate having the same reference picture list index as another candidate in the first candidate list or the second candidate list, and the second candidate having a horizontal and vertical motion vector difference from another candidate in the first candidate list or the second candidate list that is not greater than the threshold.

[0206] Aspect 18B - The apparatus of Aspect 13B, wherein the one or more processors are further configured to: construct a final geometric partitioning mode motion vector candidate list using the first candidate list and the second candidate list.

[0207] Aspect 19B - The apparatus of Aspect 18B, wherein to construct the final geometric partitioning mode motion vector candidate list using the first candidate list and the second candidate list, the one or more processors are further configured to: add the first motion vector candidates from the first candidate list to the final geometric partitioning mode motion vector candidate list; add, in the case that the final geometric partitioning mode motion vector candidate list is less than a predetermined number of candidates after adding the first motion vector candidates, the second motion vector candidates from the second candidate list to the final geometric partitioning mode motion vector candidate list; and pad, in the case that the final geometric partitioning mode motion vector candidate list is less than the predetermined number of candidates after adding the first motion vector candidates and the second motion vector candidates, zero motion vector candidates to the final geometric partitioning mode motion vector candidate list.

[0208] Aspect 20B - The apparatus of Aspect 19B, wherein the one or more processors are further configured to: perform a pruning process on the final geometric partitioning mode motion vector candidate list.

[0209] Aspect 21B - The apparatus of Aspect 19B, wherein to decode the block of video data using uni-prediction, the one or more processors are further configured to: decode the block of video data using uni-prediction and the final geometric partitioning mode motion vector candidate list.

[0210] Aspect 22B - The apparatus of Aspect 12B, further comprising: a display configured to display a picture that includes the decoded block of video data.

[0211] Aspect 23B - A non-transitory computer-readable storage medium storing instractions that, when executed, cause one or more processors of a device configured to decode video data to: determine a partitioning for the block of video data using geometric partitioning mode; construct two uni-prediction motion vector candidate lists for the block of video data; and decode the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists to generate a decoded block of video data.

[0212] Aspect 24B. The non-transitory computer-readable storage medium of Aspect 23B, wherein to construct two uni-prediction motion vector candidate lists for the block of video data, the instructions further cause the one or more processors to: construct a first candidate list of the two uni-prediction motion vector candidate lists, including interleaving first motion vector candidates from a first reference picture list with second motion vector candidates from a second reference picture list; and construct a second candidate list of the two uni-prediction motion vector candidate lists, including interleaving the second motion vector candidates from the second reference picture list with the first motion vector candidates from the first reference picture list.

[0213] Aspect 25B - The non-transitory computer-readable storage medium of Aspect 24B, wherein the instructions further cause the one or more processors to: perform a first pruning process on the first candidate list; and perform a second pruning process on the second candidate list.

[0214] Aspect 26B - An apparatus configured to encode video data, the apparatus comprising: a memory configured to store a block of video data; and one or more processors in communication with the memory, the one or more processors configured to: determine a partitioning for the block of video data using geometric partitioning mode; construct two uni-prediction motion vector candidate lists for the block of video data; and encode the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists to generate an encoded block of video data.

[0215] Aspect 27B - The apparatus of Aspect 26B, wherein to construct two uni- prediction motion vector candidate lists for the block of video data, the one or more processors are further configured to: construct a first candidate list of the two uni- prediction motion vector candidate lists, including interleaving first motion vector candidates from a first reference picture lis wtith second motion vector candidates from a second reference picture list; and construct a second candidate list of the two uni - prediction motion vector candidate lists, including interleaving the second motion vector candidates from the second reference picture list with the first motion vector candidates from the first reference picture list. [0216] Aspect 28B - The apparatus of Aspect 27B, wherein the one or more processors are further configured to: perform a first pruning process on fi thrset candidate list; and perform a second pruning process on the second candidate list.

[0217] Aspect 1C - A method of decoding video data, the method comprising: determining a partitioning for a block of video data using geometric partitioning mode; constructing two uni-prediction motion vector candidate lists for the block of video data; and decoding the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists to generate a decoded block of video data.

[0218] Aspect 2C - The method of Aspect 1C, wherein constructing two uni-prediction motion vector candidate lists for the block of video data comprises: constructing a first candidate list of the two uni-prediction motion vector candidate lists, including interleaving first motion vector candidates from a first reference picture list with second motion vector candidates from a second reference picture list; and constructing a second candidate list of the two uni-prediction motion vector candidate lists, including interleaving the second motion vector candidates from the second reference picture list with the first motion vector candidates from the first reference picture list.

[0219] Aspect 3C - The method of Aspect 2C, wherein interleaving first motion vector candidates from the first reference picture list with second motion vector candidates from the second reference picture list comprises adding the first motion vector candidates and the second motion vector candidates to the first candidate list in an alternating fashion wherein a candidate from the first motion vector candidates is added first.

[0220] Aspect 4C - The method of any of Aspects 2C-3C, wherein interleaving second motion vector candidates from the second reference picture list with first motion vector candidates from the first reference picture list comprises adding the second motion vector candidates and the first motion vector candidates to the second candidate list in an alternating fashion wherein a candidate from the second motion vector candidates is added first.

[0221] Aspect 5C - The method of any of Aspects 2C-4C, further comprising: performing a first pruning process on the first candidate list; and performing a second pruning process on the second candidate list.

[0222] Aspect 6C - The method of Aspect 5C, wherein performing the first pruning process on the first candidate list comprises: removing a first candidate from the first candidate list based on the first candidate having the same reference picture list as another candidate in the first candidate list, the first candidate having the same reference picture list index as another candidate in the first candidate list, and the first candidate having a horizontal and vertical motion vector difference from another candidate in the first candidate list that is not greater than a threshold, and wherein performing the second pruning process on the second candidate list comprises: removing a second candidate from the second candidate list based on the second candidate having the same reference picture list as another candidate the first candidate list or in the second candidate list, the second candidate having the same reference picture list index as another candidate the first candidate list or in the second candidate list, and the second candidate having a horizontal and vertical motion vector difference from another candidate in the first candidate list or the second candidate list that is not greater than the threshold.

[0223] Aspect 7C - The method of any of Aspects 2C-6C, further comprising: constructing a final geometric partitioning mode motion vector candidate list using the first candidate list and the second candidate list.

[0224] Aspect 8C - The method of Aspect 7C, wherein constructing the final geometric partitioning mode motion vector candidate list using the first candidate list and the second candidate list comprises: adding the first motion vector candidates from the first candidate list to the final geometric partitioning mode motion vector candidate list; adding, in the case that the final geometric partitioning mode motion vector candidate list is less than a predetermined number of candidates after adding the first motion vector candidates, the second motion vector candidates from the second candidate list to the final geometric partitioning mode motion vector candidate list; and padding, in the case that the final geometric partitioning mode motion vector candidate list is less than the predetermined number of candidates after adding the first motion vector candidates and the second motion vector candidates, zero motion vector candidates to the final geometric partitioning mode motion vector candidate list.

[0225] Aspect 9C - The method of any of Aspects 7C-8C, further comprising: performing a pruning process on the final geometric partitioning mode motion vector candidate list.

[0226] Aspect IOC - The method of any of Aspects 7C-9C, wherein decoding the block of video data using uni-prediction comprises: decoding b thloeck of video data using uni-prediction and the final geometric partitioning mode motion vector candidate list. [0227] Aspect 11C - The method of any of Aspects 1C-10C, further comprising: displaying a picture that includes the decoded block of video data.

[0228] Aspect 12C - An apparatus configured to decode video data, the apparatus comprising: a memory configured to store a block of video data; and one or more processors in communication with the memory, the one or more processors configured to: determine a partitioning for the block of video data using geometric partitioning mode; construct two uni-prediction motion vector candidate lists for the block of video data; and decode the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists to generate a decoded block of video data.

[0229] Aspect 13C - The apparatus of Aspect 12C, wherein to construct two uni- prediction motion vector candidate lists for the block of video data, the one or more processors are further configured to: construct a first candidate list of the two uni- prediction motion vector candidate lists, including interleaving first motion vector candidates from a first reference picture list with second motion vector candidates from a second reference picture list; and construct a second candidate list of the two uni - prediction motion vector candidate lists, including interleaving the second motion vector candidates from the second reference picture list with the first motion vector candidates from the first reference picture list.

[0230] Aspect 14C - The apparatus of Aspect 13C, wherein to interleave first motion vector candidates from the first reference picture list with second motion vector candidates from the second reference picture list, the one or more processors are configured to add the first motion vector candidates and the second motion vector candidates to the first candidate list in an alternating fashion wherein a candidate from the first motion vector candidates is added first.

[0231] Aspect 15C - The apparatus of any of Aspects 13C-14C, wherein to interleave second motion vector candidates from the second reference picture list with first motion vector candidates from the first reference picture list, the one or more processors are configured to add the second motion vector candidates and the first motion vector candidates to the second candidate list in an alternating fashion wherein a candidate from the second motion vector candidates is added first.

[0232] Aspect 16C - The apparatus of any of Aspects 13C-15C, wherein the one or more processors are further configured to: perform a first pruning process on the first candidate list; and perform a second pruning process on the second candidate list. [0233] Aspect 17C - The apparatus of Aspect 16C, wherein to perform the first pruning process on the first candidate list, the one or more processors are configured to: remove a first candidate from the first candidate list based on the first candidate having the same reference picture list as another candidate in the first candidate , l tihste first candidate having the same reference picture list index as another candidate in the first candidate fist, and the first candidate having a horizontal and vertical motion vector difference from another candidate in the first candidate li thstat is not greater than a threshold, and wherein to perform the second pruning process on the second candidate list, the one or more processors are configured to: remove a second candidate from the second candidate list based on the second candidate having the same reference picture list as another candidate in the first candidate lis otr the second candidate list, the second candidate having the same reference picture lis intdex as another candidate in the first candidate list or the second candidate li,st and the second candidate having a horizontal and vertical motion vector difference from another candidate in the first candidate or list the second candidate list that is not greater than t thhereshold.

[0234] Aspect 18C - The apparatus of any of Aspects 13C-17C, wherein the one or more processors are further configured to: construct a final geometric partitioning mode motion vector candidate list using the first candidate list and the second candidate list. [0235] Aspect 19C - The apparatus of Aspect 18C, wherein to construct the final geometric partitioning mode motion vector candidate list using the first candidate list and the second candidate list, the one or more processors are further configured to: add the first motion vector candidates from the first candidate list to the final geometric partitioning mode motion vector candidate list; add, in the case that the final geometric partitioning mode motion vector candidate list is less than a predetermined number of candidates after adding the first motion vector candidates, the second motion vector candidates from the second candidate list to the final geometric partitioning mode motion vector candidate list; and pad, in the case that the final geometric partitioning mode motion vector candidate list is less than the predetermined number of candidates after adding the first motion vector candidates and the second motion vector candidates, zero motion vector candidates to the final geometric partitioning mode motion vector candidate list.

[0236] Aspect 20C - The apparatus of Aspect 19C, wherein the one or more processors are further configured to: perform a pruning process on the final geometric partitioning mode motion vector candidate list. [0237] Aspect 21C - The apparatus of any of Aspects 19C-20C, wherein to decode the block of video data using uni-prediction, the one or more processors are further configured to: decode the block of video data using uni-prediction and the final geometric partitioning mode motion vector candidate list.

[0238] Aspect 22C - The apparatus of any of Aspects 12C-21C, further comprising: a display configured to display a picture that includes the decoded block of video data. [0239] It is to be recognized that depending on the example, certain acts or events of any of the techniques described herein can be performed in a different sequence, may be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the techniques). Moreover, in certain examples, acts or events may be performed concurrently, e.g., through multi-threaded processing, interrupt processing, or multiple processors, rather than sequentially.

[0240] In one or more examples, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media, which corresponds to a tangible medium such as data storage media, or communication media including any medium that facilitates transfer of a computer program from one place to another, e.g., according to a communication protocol. In this manner, computer- readable media generally may correspond to (1) tangible computer-readable storage media which is non-transitory or (2) a communication medium such as a signal or carrier wave. Data storage media may be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, code and/or data structures for implementation of the techniques described in this disclosure. A computer program product may include a computer-readable medium.

[0241] By way of example, and not limitation, such computer-readable storage media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage, or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. It should be understood, however, that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transitory media, but are instead directed to non-transitory, tangible storage media. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0242] Instructions may be executed by one or more processors, such as one or more DSPs, general purpose microprocessors, ASICs, FPGAs, or other equivalent integrated or discrete logic circuitry. Accordingly, the terms “processor” and “processing circuitry,” as used herein may refer to any of the foregoing structures or any other structure suitable for implementation of the techniques described herein. In addition, in some aspects, the functionality described herein may be provided within dedicated hardware and/or software modules configured for encoding and decoding, or incorporated in a combined codec. Also, the techniques could be fully implemented in one or more circuits or logic elements.

[0243] The techniques of this disclosure may be implemented in a wide variety of devices or apparatuses, including a wireless handset, an integrated circuit (IC) or a set of ICs (e.g., a chip set). Various components, modules, or units are described in this disclosure to emphasize functional aspects of devices configured to perform the disclosed techniques, but do not necessarily require realization by different hardware units. Rather, as described above, various units may be combined in a codec hardware unit or provided by a collection of interoperative hardware units, including one or more processors as described above, in conjunction with suitable software and/or firmware.

[0244] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

WHAT IS CLAIMED IS:

1. A method of decoding video data, the method comprising: determining a partitioning for a block of video data using geometric partitioning mode; constructing two uni-prediction motion vector candidate lists for the block of video data; and decoding the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists to generate a decoded block of video data.

2. The method of claim 1, wherein constructing two uni-prediction motion vector candidate lists for the block of video data comprises: constructing a first candidate list of the two uni-prediction motion vector candidate lists, including interleaving first motion vector candidates from a first reference picture list with second motion vector candidates from a second reference picture list; and constructing a second candidate list of the two uni-prediction motion vector candidate lists, including interleaving the second motion vector candidates from the second reference picture list with the first motion vector candidates from the first reference picture list.

3. The method of claim 2, wherein interleaving first motion vector candidates from the first reference picture list with second motion vector candidates from the second reference picture list comprises adding the first motion vector candidates and the second motion vector candidates to the first candidate list in an alternating fashion wherein a candidate from the first motion vector candidates is added first.

4. The method of claim 2, wherein interleaving second motion vector candidates from the second reference picture list with first motion vector candidates from the first reference picture list comprises adding the second motion vector candidates and the first motion vector candidates to the second candidate list in an alternating fashion wherein a candidate from the second motion vector candidates is added first.

5. The method of claim 2, further comprising: performing a first pruning process on the first candidate list; and performing a second pruning process on the second candidate list.

6. The method of claim 5, wherein performing the first pruning process on the first candidate list comprises: removing a first candidate from the first candidate list based on the first candidate having the same reference picture list as another candidate in the first candidate list, the first candidate having the same reference picture list index as another candidate in the first candidate list, and the first candidate having a horizontal and vertical motion vector difference from another candidate in the first candidate list that is not greater than a threshold, and wherein performing the second pruning process on the second candidate list comprises: removing a second candidate from the second candidate list based on the second candidate having the same reference picture list as another candidate in the first candidate list or the second candidate list, the second candidate having the same reference picture list index as another candidate in the first candidate list or the second candidate list, and the second candidate having a horizontal and vertical motion vector difference from another candidate in the first candidate list or the second candidate list that is not greater than the threshold.

7. The method of claim 2, further comprising: constructing a final geometric partitioning mode motion vector candidate list using the first candidate list and the second candidate list.

8. The method of claim 7, wherein constructing the final geometric partitioning mode motion vector candidate list using the first candidate list and the second candidate list comprises: adding the first motion vector candidates from the first candidate list to the final geometric partitioning mode motion vector candidate list; adding, in the case that the final geometric partitioning mode motion vector candidate list is less than a predetermined number of candidates after adding the first motion vector candidates, the second motion vector candidates from the second candidate list to the final geometric partitioning mode motion vector candidate list; and padding, in the case that the final geometric partitioning mode motion vector candidate list is less than the predetermined number of candidates after adding the first motion vector candidates and the second motion vector candidates, zero motion vector candidates to the final geometric partitioning mode motion vector candidate list.

9. The method of claim 7, further comprising: performing a pruning process on the final geometric partitioning mode motion vector candidate list.

10. The method of claim 7, wherein decoding the block of video data using uni- prediction comprises: decoding the block of video data using uni-prediction and the final geometric partitioning mode motion vector candidate list.

11. The method of claim 1, further comprising: displaying a picture that includes the decoded block of video data.

12. An apparatus configured to decode video data, the apparatus comprising: a memory configured to store a block of video data; and one or more processors in communication with the memory, the one or more processors configured to: determine a partitioning for the block of video data using geometric partitioning mode; construct two uni-prediction motion vector candidate lists for the block of video data; and decode the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists to generate a decoded block of video data.

13. The apparatus of claim 12, wherein to construct two uni-prediction motion vector candidate lists for the block of video data, the one or more processors are further configured to: construct a first candidate list of the two uni-prediction motion vector candidate lists, including interleaving first motion vector candidates from a first reference picture list with second motion vector candidates from a second reference picture list; and construct a second candidate list of the two uni-prediction motion vector candidate lists, including interleaving the second motion vector candidates from the second reference picture list with the first motion vector candidates from the first reference picture list.

14. The apparatus of claim 13, wherein to interleave first motion vector candidates from the first reference picture list with second motion vector candidates from the second reference picture list, the one or more processors are configured to add the first motion vector candidates and the second motion vector candidates to the first candidate list in an alternating fashion wherein a candidate from the first motion vector candidates is added first.

15. The apparatus of claim 13, wherein to interleave second motion vector candidates from the second reference picture list with first motion vector candidates from the first reference picture list, the one or more processors are configured to add the second motion vector candidates and th fierst motion vector candidates to the second candidate list in an alternating fashion wherein a candidate from the second motion vector candidates is added first.

16. The apparatus of claim 13, wherein the one or more processors are further configured to: perform a first pruning process on the first candidate list; and perform a second pruning process on the second candidate list.

17. The apparatus of claim 16, wherein to perform the first pruning process on the first candidate list, the one or more processors are configured to: remove a first candidate from the first candidate list based on the first candidate having the same reference picture list as another candidate in the first candidate list, the first candidate having the same reference picture list index as another candidate in the first candidate list, and the first candidate having a horizontal and vertical motion vector difference from another candidate in the first candidate list that is not greater than a threshold, and wherein to perform the second pruning process on the second candidate list, the one or more processors are configured to: remove a second candidate from the second candidate list based on the second candidate having the same reference picture list as another candidate in the first candidate list or the second candidate list, the second candidate having the same reference picture list index as another candidate in the first candidate list or the second candidate list, and the second candidate having a horizontal and vertical motion vector difference from another candidate in the first candidate list or the second candidate list that is not greater than the threshold.

18. The apparatus of claim 13, wherein the one or more processors are further configured to: construct a final geometric partitioning mode motion vector candidate list using the first candidate list and the second candidate list.

19. The apparatus of claim 18, wherein to construct the final geometric partitioning mode motion vector candidate list using the first candidate list and the second candidate list, the one or more processors are further configured to: add the first motion vector candidates from the first candidate list to the final geometric partitioning mode motion vector candidate list; add, in the case that the final geometric partitioning mode motion vector candidate list is less than a predetermined number of candidates after adding the first motion vector candidates, the second motion vector candidates from the second candidate list to the final geometric partitioning mode motion vector candidate list; and pad, in the case that the final geometric partitioning mode motion vector candidate list is less than the predetermined number of candidates after adding the first motion vector candidates and the second motion vector candidates, zero motion vector candidates to the final geometric partitioning mode motion vector candidate list.

20. The apparatus of claim 19, wherein the one or more processors are further configured to: perform a pruning process on the final geometric partitioning mode motion vector candidate list.

21. The apparatus of claim 19, wherein to decode the block of video data using uni- prediction, the one or more processors are further configured to: decode the block of video data using uni-prediction and the final geometric partitioning mode motion vector candidate list.

22. The apparatus of claim 12, further comprising: a display configured to display a picture that includes the decoded block of video data.

23. A non-transitory computer-readable storage medium storing instructions that, when executed, cause one or more processors of a device configured to decode video data to: determine a partitioning for a block of video data using geometric partitioning mode; construct two uni-prediction motion vector candidate lists for the block of video data; and decode the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists to generate a decoded block of video data.

24. The non-transitory computer-readable storage medium of claim 23, wherein to construct two uni-prediction motion vector candidate lists for the block of video data, the instractions further cause the one or more processors to: construct a first candidate list of the two uni-prediction motion vector candidate lists, including interleaving first motion vector candidates from a first reference picture list with second motion vector candidates from a second reference picture list; and construct a second candidate list of the two uni-prediction motion vector candidate lists, including interleaving the second motion vector candidates from the second reference picture list with the first motion vector candidates from the first reference picture list.

25. The non-transitory computer-readable storage medium of claim 24, wherein the instructions further cause the one or more processors to: perform a first pruning process on the first candidate list; and perform a second pruning process on the second candidate list.

26. An apparatus configured to encode video data, the apparatus comprising: a memory configured to store a block of video data; and one or more processors in communication with the memory, the one or more processors configured to: determine a partitioning for the block of video data using geometric partitioning mode; construct two uni-prediction motion vector candidate lists for the block of video data; and encode the block of video data using uni-prediction based on at least one of the two uni-prediction motion vector candidate lists to generate an encoded block of video data.

27. The apparatus of claim 26, wherein to construct two uni-prediction motion vector candidate lists for the block of video data, the one or more processors are further configured to: construct a first candidate list of the two uni-prediction motion vector candidate lists, including interleaving first motion vector candidates from a first reference picture list with second motion vector candidates from a second reference picture list; and construct a second candidate list of the two uni-prediction motion vector candidate lists, including interleaving the second motion vector candidates from the second reference picture list with the first motion vector candidates from the first reference picture list.

28. The apparatus of claim 27, wherein the one or more processors are further configured to: perform a first pruning process on the first candidate list; and perform a second pruning process on the second candidate list.