Affine Motion Prediction

Abstract

A video encoder and a video decoder are configured to encode and decode a block of video data using affine motion prediction. The affine motion prediction may include predicting a control point motion vector using an affine advanced motion vector prediction (AMVP) motion vector predictor list. The video encoder and the video decoder may be configured to construct an affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, wherein the affine AMVP motion vector predictor list includes one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector.

Description

[0001] This application claims priority to U.S. Patent Application No. 16 / 550,910, filed on August 26, 2019, which claims priority to U.S. Provisional Patent Application No. 62 / 723,919, filed on August 28, 2018, U.S. Provisional Patent Application No. 62 / 728,489, filed on September 7, 2018, and U.S. Provisional Patent Application No. 62 / 730,814, filed on September 13, 2018, the entire contents of each of which are incorporated herein by reference. Technical Field

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

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

[0004] Video coding techniques include spatial (intra-picture) prediction and / or temporal (inter-picture) prediction to reduce or eliminate redundancy inherent in video sequences. For block-based video coding, a video slice (e.g., a video picture or a portion of a video picture) may be partitioned into video blocks, which may also be referred to as coding tree units (CTUs), coding units (CUs), and / or coding nodes. For video blocks in an intra-coded (I) slice of a picture, spatial prediction relative to reference samples in neighboring blocks in the same picture may be used for encoding. For video blocks in an inter-coded (P or B) slice of a picture, spatial prediction relative to reference samples in neighboring blocks in the same picture or temporal prediction relative to reference samples in other reference pictures may be used. A picture may be referred to as a frame, and a reference picture may be referred to as a reference frame. Summary of the invention

[0005] In general, the present disclosure describes techniques related to inter-frame prediction in video codecs. More specifically, the present disclosure describes methods and devices for performing affine motion prediction techniques. Affine motion prediction is a motion prediction technique that uses more complex motion models (e.g., rotation, scaling, magnification, etc.) than simple translational motion (e.g., subtracting the (x, y) position of a predictor block from the (x, y) position of a currently decoded block). Multiple affine motion models can be used in affine motion prediction. For example, a 4-parameter affine motion model can use two motion vectors (called control point motion vectors) determined at two corners of a block. The x and y components of each control point motion vector are parameters in a 4-parameter affine motion model. A 6-parameter affine motion model can use three control point motion vectors at three corners of a block.

[0006] The video encoder may be configured to predict the value of the control point motion vector based on the control point motion vectors and / or standard (e.g., translation) motion vectors from neighboring blocks, rather than decoding the control point motion vectors for each block. Such control point motion vectors and / or standard (e.g., translation) motion vectors from neighboring blocks may be referred to as affine motion vector predictors. The video encoder and video decoder may be configured to construct an affine motion vector predictor list based on some predetermined rules. The video encoder then instructs the video decoder which motion vector predictor in the list to use by signaling an index value to the list.

[0007] Affine motion vector predictors may include two example types: inherited affine motion vector predictors and constructed affine motion vector predictors. Inherited affine motion vector predictors are derived from control point motion vectors of neighboring blocks. Constructed affine motion vector predictors are derived from standard (e.g., translation) motion vectors of neighboring blocks. Thus, inherited affine motion vector predictors come from neighboring blocks that were coded using affine motion prediction, while constructed affine motion vector predictors come from neighboring blocks that were coded using standard (e.g., translation) motion prediction (typically inter-frame prediction).

[0008] Affine motion vector prediction can be performed in one of several prediction modes, including advanced motion vector prediction (AMVP) mode and merge mode. In both affine AMVP mode and affine merge mode, the video encoder constructs a list of affine motion vector predictors. However, the technique for constructing the list may be different for each mode. In affine AMVP mode, in addition to identifying the affine motion vector predictor from the list used, the motion vector difference is also signaled. The motion vector difference is the difference between the value of the actual control point motion vector determined for the current block and the value of the affine motion vector predictor. In affine merge mode, the motion vector difference is not sent. Instead, the value of the indicated affine motion vector predictor is used as the control point motion vector for the block.

[0009] In some examples, the present disclosure describes techniques for constructing an affine motion vector predictor list for an affine AMVP mode. In one example, the affine motion vector predictor list is constructed using the following technique. First, if available, the video decoder inserts one or more inherited affine motion vector predictors derived from neighboring candidate blocks. If the number of existing predictors in the list is less than a predefined maximum number, the video decoder inserts a constructed affine motion vector predictor if available. If the number of existing predictors in the list is still less than the predefined maximum number, the video decoder inserts an affine motion vector predictor whose all control point motion vectors (MVs) are equal to a specified MV. Thus, for some example blocks, the affine motion vector predictor list may include one of an inherited affine motion vector predictor or a constructed affine motion vector predictor, together with an affine motion vector predictor that makes all control point MVs equal to a specified MV.

[0010] In one example of the present disclosure, a method for decoding video data includes receiving a video data block encoded using an affine advanced motion vector prediction (AMVP) mode, constructing an affine AMVP motion vector predictor list of candidate control point motion vectors for the video data block, the affine AMVP motion vector predictor list including one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector, determining a control point motion vector for the video data block from the affine AMVP motion vector predictor list, and decoding the video data block using the determined control point motion vector.

[0011] In another example of the present disclosure, a device is configured to decode video data, the device including a component for receiving a video data block encoded using an affine advanced motion vector prediction (AMVP) mode, a component for constructing an affine AMVP motion vector predictor list of candidate control point motion vectors for the video data block, the affine AMVP motion vector predictor list including one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector, a component for determining the control point motion vector for the video data block from the affine AMVP motion vector predictor list, and a component for decoding the video data block using the determined control point motion vector.

[0012] In another example, the present disclosure describes a non-transitory computer-readable storage medium storing instructions that, when executed, cause one or more processors to receive a block of video data encoded using an affine advanced motion vector prediction (AMVP) mode, construct an affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, the affine AMVP motion vector predictor list including one or more affine motion vector predictors that cause all control point motion vectors to be equal to a specified motion vector, determine a control point motion vector for the block of video data from the affine AMVP motion vector predictor list, and decode the block of video data using the determined control point motion vector.

[0013] In another example of the present disclosure, a method for encoding video data includes receiving a block of video data to be encoded using an affine advanced motion vector prediction (AMVP) mode, constructing an affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, the affine AMVP motion vector predictor list including one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector, determining the control point motion vector for the block of video data from the affine AMVP motion vector predictor list, and encoding the block of video data using the determined control point motion vector.

[0014] In another example of the present disclosure, a device is configured to encode video data, the device including a memory configured to store a video data block to be encoded using an affine advanced motion vector prediction (AMVP) mode, and one or more processors in communication with the memory, the one or more processors configured to receive the video data block, construct an affine AMVP motion vector predictor list of candidate control point motion vectors for the video data block, the affine AMVP motion vector predictor list including one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector, determine the control point motion vector for the video data block from the affine AMVP motion vector predictor list, and encode the video data block using the determined control point motion vector.

[0015] In another example, the present disclosure describes a non-transitory computer-readable storage medium storing instructions that, when executed, cause one or more processors to receive a block of video data to be encoded using an affine advanced motion vector prediction (AMVP) mode, construct an affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, the affine AMVP motion vector predictor list including one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector, determine a control point motion vector for the block of video data from the affine AMVP motion vector predictor list, and encode the block of video data using the determined control point motion vector.

[0016] The details of one or more examples are set forth in the accompanying drawings and the description below.Other features, objects, and advantages will be apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0019] Figure 3 is a block diagram illustrating an example video encoder that may perform the techniques of this disclosure.

[0020] Figure 4 is a block diagram illustrating an example video decoder that may perform the techniques of this disclosure.

[0021] Figure 5 is a conceptual diagram illustrating example motion vectors for a 6-parameter affine motion model.

[0022] Figure 6 is a conceptual diagram showing example motion vectors for a simplified 4-parameter affine motion model.

[0023] Figure 7 is a conceptual diagram showing an example inherited affine motion vector predictor.

[0024] Figure 8 is a conceptual diagram illustrating example candidate blocks for an inherited affine motion vector predictor.

[0025] Fig. 9 is a conceptual diagram illustrating an example row buffer.

[0026] Fig.10 is a conceptual diagram showing example neighboring affine blocks that extend beyond a line buffer.

[0027] Fig.11 is a conceptual diagram illustrating an example current block for flexible decoder order.

[0028] Fig.12 is a flow chart illustrating example operation of a video encoder.

[0029] Fig.13 is a flow chart illustrating example operation of a video decoder.

[0030] Fig.14 is a flow chart illustrating another example operation of a video encoder.

[0031] Fig.15 is a flow chart illustrating another example operation of a video decoder. DETAILED DESCRIPTION

[0032] Figure 1 1 is a block diagram illustrating an example video encoding and decoding system 100 that can perform the techniques of the present disclosure. The techniques of the present disclosure are generally directed to decoding (encoding and / or decoding) video data. Generally, video data includes any data used to process video. Thus, video data can include original undecoded video, encoded video, decoded (e.g., reconstructed) video, and video metadata (such as signaling data).

[0033] like Figure 1As shown, in this example, system 100 includes a source device 102 that provides encoded video data to be decoded and displayed by a target device 116. In particular, source device 102 provides the video data to target device 116 via computer-readable medium 110. Source device 102 and target device 116 may include any of a variety of devices, including desktop computers, notebooks (i.e., laptop computers), tablet computers, set-top boxes, handheld phones (such as smartphones), televisions, cameras, display devices, digital media players, video game consoles, video streaming devices, etc. In some cases, source device 102 and target device 116 may be equipped for wireless communication and, therefore, may be referred to as wireless communication devices.

[0034] exist Figure 1 In the example of, source device 102 comprises video source 104 (such as camera), memory 106, video encoder 200 and output interface 108. Target device 116 comprises input interface 122, video decoder 300, memory 120 and display device 118. According to the present disclosure, the video encoder 200 of source device 102 and the video decoder 300 of target device 116 can be configured to apply the technology for affine motion prediction. Thus, source device 102 represents an example of video encoding device, and target device 116 represents an example of video decoding device. In other examples, source device and target device may include other components or arrangements. For example, source device 102 may receive video data from an external video source such as an external camera. Similarly, target device 116 may be connected to an external display device via an interface without including an integrated display device.

[0035] like Figure 1 The system 100 shown is only an example. Generally, any digital video encoding and / or decoding device can perform the technology for affine motion prediction. The source device 102 and the target device 116 are only examples of such decoding devices, wherein the source device 102 generates decoded video data for transmission to the target device 116. The present disclosure represents the "decoding" device as a device that performs data decoding (encoding and / or decoding). Thus, the video encoder 200 and the video decoder 300 represent examples of decoding devices, specifically, video encoders and video decoders, respectively. In some examples, the source device 102 and the target device 116 can operate in a substantially symmetrical manner, so that each of the source device 102 and the target device 116 includes a video encoding and decoding component. Thus, the system 100 can support one-way or two-way video transmission between the source device 102 and the target device 116, such as for video streaming, video playback, video broadcasting or video telephony.

[0036] Generally, the video source 104 represents a source of video data (i.e., original, undecoded video data), and provides a sequence of continuous pictures (also referred to as "frames") of the video data to the video encoder 200, which encodes the data of the pictures. The video source 104 of the source device 102 may include a video capture device, such as a camera, a video archive including previously captured original video, and / or a video feed interface for receiving video from a video content provider. As a further alternative, the video source 104 may generate computer graphics-based data as a source video, or a combination of live video, archived video, and computer-generated video. In each case, the video encoder 200 encodes the captured, pre-captured, or computer-generated video data. The video encoder 200 may rearrange the pictures from the receiving order (sometimes referred to as "display order") to the decoding order for decoding. The video encoder 200 may generate a bitstream including the encoded video data. Then, the source device 102 may output the encoded video data to a computer-readable medium 110 via the output interface 108, and receive and / or retrieve the input interface 122 of the target device 116, for example.

[0037] The memory 106 of the source device 102 and the memory 120 of the target device 116 represent general purpose memory. In some examples, the memories 106, 120 can store original video data, such as original video from the video source 104 and original decoded video data from the video decoder 300. Additionally or alternatively, the memories 106, 120 can store software instructions that can be executed by, for example, the video encoder 200 and the video decoder 300, respectively. Although the memory 106 and the memory 120 are shown separately from the video encoder 200 and the video decoder 300 in this example, it should be understood that the video encoder 200 and the video decoder 300 can also include internal memory that achieves functionally similar or equivalent purposes. Further, the memories 106, 120 can store, for example, encoded video data output from the video encoder 200 and input to the video decoder 300. In some examples, portions of the memories 106, 120 can be allocated as one or more video buffers, for example, to store original decoded and / or encoded video data.

[0038] The computer-readable medium 110 may represent any type of medium or device capable of transmitting the encoded video data from the source device 102 to the target device 116. In some examples, the computer-readable medium 110 represents a communication medium to enable the source device 102 to directly send the encoded video data to the target device 116 in real time, for example, via a radio frequency network or a computer-based network. According to a communication standard such as a wireless communication protocol, the output interface 108 may modulate the transmission signal including the encoded video data, and the input interface 122 may modulate the received transmission signal. The communication medium may include any wireless or wired communication medium, such as a radio frequency (RF) spectrum or one or more physical transmission lines. The communication medium may form a portion of a packet-based network such as a local area network, a wide area network, or a global network such as the Internet. The communication medium may include a router, a switch, a base station, or any other equipment that facilitates communication from the source device 102 to the target device 116.

[0039] In some examples, computer-readable medium 110 may include storage device 112. Source device 102 may output the encoded data from output interface 108 to storage device 112. Similarly, target device 116 may access the encoded data from storage device 112 via input interface 122. Storage device 112 may include any of a variety of distributed or locally accessed data storage media, such as a hard disk, Blu-ray disc, DVD, CD-ROM, flash memory, volatile or non-volatile memory, or any other suitable digital storage medium for storing encoded video data.

[0040] In some examples, the computer-readable medium 110 may include a file server 114 or another intermediate storage device that can store the encoded video data generated by the source device 102. The source device 102 may output the encoded video data to the file server 114. The target device 116 may access the stored video data from the file server 114 via streaming or downloading. The file server 114 may be any type of server device capable of storing the encoded video data and sending the encoded video data to the target device 116. The file server 114 may represent a network server (e.g., for a website), a file transfer protocol (FTP) server, a content delivery network device, or a network attached storage (NAS) device. The target device 116 may access the encoded video data from the file server 114 through any standard data connection including an Internet connection. This may include a wireless channel (e.g., a Wi-Fi connection), a wired connection (e.g., a digital subscriber line (DSL), a cable modem, etc.), or a combination of the two suitable for accessing the encoded video data stored on the file server 114. The file server 114 and the input interface 122 may be configured to operate according to a streaming protocol, a download transmission protocol, or a combination thereof.

[0041] Output interface 108 and input interface 122 may represent wireless transmitters / receivers, modems, wired networking components (e.g., Ethernet cards), wireless communication components that operate according to any of the various IEEE 802.11 standards, or other physical components. In examples where output interface 108 and input interface 122 include wireless components, output interface 108 and input interface 122 may be configured to transmit data, such as encoded video data, according to a cellular communication standard such as 4G, 4G-LTE (Long Term Evolution), LTE Advanced, 5G, or the like. In certain examples where output interface 108 includes a wireless transmitter, output interface 108 and input interface 122 may be configured to transmit data, such as encoded video data, according to other wireless standards, such as the IEEE 802.11 specification, the IEEE 802.15 specification (e.g., ZigBee TM ), Bluetooth TM Standards, etc., to transmit data such as encoded video data. In some examples, source device 102 and / or target device 116 may include respective system-on-a-chip (SoC) devices. For example, source device 102 may include an SoC device to perform functions attributed to video encoder 200 and / or output interface 108, and target device 116 may include an SoC device to perform functions attributed to video decoder 300 and / or input interface 122.

[0042] The technology disclosed herein can be applied to video decoding to support any of a variety of multimedia applications, such as over-the-air television broadcasting, cable television transmission, satellite television transmission, Internet streaming video transmission such as Dynamic Adaptive Streaming over HTTP (DASH), digital video encoded onto a data storage medium, decoding of digital video stored on a data storage medium, or other applications.

[0043] The input interface 122 of the target device 116 receives an encoded video bitstream from the computer-readable medium 110 (e.g., a communication medium, a storage device 112, a file server 114, etc.). The encoded video bitstream from the computer-readable medium 110 may include signaling information defined by the video encoder 200 and also used by the video decoder 300, such as syntax elements having values ​​describing characteristics and / or processing of video blocks or other decoding units (e.g., slices, pictures, groups of pictures, sequences, etc.). The display device 118 displays decoded pictures of the decoded video data to a user. The display device 118 may represent any of a variety of display devices such as a cathode ray tube (CRT), a liquid crystal display (LCD), a plasma display, an organic light emitting diode (OLED) display, or another type of display device.

[0044] Although not in Figure 1, but in some examples, each of the video encoder 200 and the video decoder 300 may be integrated with an audio encoder and / or an audio decoder and may include appropriate MUX-DEMUX units or other hardware and / or software to process multiplexed streams including audio and video in a common data stream. If applicable, the MUX-DEMUX unit may conform to the ITU H.223 multiplexer protocol or other protocols such as the User Datagram Protocol (UDP).

[0045] Each of the video encoder 200 and the video decoder 300 can be implemented as any of a variety of suitable encoder and / or decoder circuits, such as one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), discrete logic, software, hardware, firmware, or any combination thereof. When the technology is partially implemented in software, the device can store instructions for the software in a suitable non-temporary computer-readable medium and use one or more processors to execute the instructions in hardware to perform the technology of the present disclosure. Each of the video encoder 200 and the video decoder 300 can be included in one or more encoders or decoders, both of which can be integrated as part of a combined encoder / decoder (CODEC) in the respective device. The device including the video encoder 200 and / or the video decoder 300 can include an integrated circuit, a microprocessor, and / or a wireless communication device such as a cellular phone.

[0046] As will be described in more detail below, the video encoder 200 and the video decoder 300 can be configured to encode and decode blocks of video data using affine motion prediction. Affine motion prediction is a motion prediction technique that uses motion of more complex motions (e.g., rotation, scaling, magnification, etc.) than simple translational motion (e.g., subtracting the (x, y) position of the predictor block from the (x, y) position of the currently decoded block). The video encoder 200 and the video decoder 300 can use multiple affine motion models in affine motion prediction. For example, a 4-parameter affine motion model can use two motion vectors (called control point motion vectors) determined at two corners of the block. The x and y components of each control point motion vector are parameters in the 4-parameter affine motion model. The 6-parameter affine motion model can use three control point motion vectors at the three corners of the block.

[0047] The video encoder 200 and the video decoder 300 may be configured to predict the value of the control point motion vector based on the control point motion vectors and / or standard (e.g., translation) motion vectors from neighboring blocks, rather than decoding the control point motion vectors for each block. Such control point motion vectors and / or standard (e.g., translation) motion vectors from neighboring blocks may be referred to as affine motion vector predictors. The video encoder 200 and the video decoder 300 may be configured to construct an affine motion vector predictor list based on some predetermined rules. The video encoder 200 may then instruct the video decoder 300 which motion vector predictor in the list to be used by signaling an index value to the list.

[0048] Affine motion vector prediction can include two example types: inherited affine motion vector predictors and constructed affine motion vector predictors. Inherited affine motion vector predictors are derived from control point motion vectors of neighboring blocks. Constructed affine motion vector predictors are derived from standard (e.g., translation) motion vectors of neighboring blocks. Thus, inherited affine motion vector predictors come from neighboring blocks that were coded using affine motion prediction, while constructed affine motion vector predictors come from neighboring blocks that were coded using standard (e.g., translation) motion prediction (usually inter-frame prediction).

[0049] The video encoder 200 and the video decoder 300 can perform affine motion vector prediction in one of several prediction modes, including advanced motion vector prediction (AMVP) mode and merge mode. In affine AMVP mode and affine merge mode, the video encoder 200 and the video decoder 300 construct an affine motion vector predictor list. However, the technique for constructing the list may be different for each mode. In affine AMVP mode, in addition to identifying the affine motion vector predictor from the list used, a motion vector difference is also signaled. The motion vector difference is the difference between the value of the actual control point motion vector determined for the current block and the value of the affine motion vector predictor. In affine merge mode, the motion vector difference is not sent. Instead, the value of the indicated affine motion vector predictor is used as the control point motion vector for the block.

[0050] In some examples, the present disclosure describes techniques for constructing an affine motion vector predictor list for an affine AMVP mode. In one example, the video encoder 200 and the video decoder 300 use the following techniques to construct an affine motion vector predictor list. First, if available, the video encoder 200 and / or the video decoder 300 insert one or more inherited affine motion vector predictors derived from neighboring candidate blocks. In some examples, there may not be an inherited affine motion vector predictor. If the number of existing predictors in the list is less than a predefined maximum number, and if available, the video encoder 200 and / or the video decoder 300 inserts a constructed affine motion vector predictor. In some examples, there may not be a constructed affine motion vector predictor. If the number of existing predictors in the list is still less than the predefined maximum number, the video encoder 200 and / or the video decoder 300 insert an affine motion vector predictor that makes all control point MVs equal to a specified MV. Thus, for some example blocks, the affine motion vector predictor list will include one or more inherited affine motion vector predictors and / or one or more constructed affine motion vector predictors, together with an affine motion vector predictor that makes all control point MVs equal to a specified MV.

[0051] In another example of the present disclosure, a video decoder 300 includes a memory configured to store a video data block encoded using an affine advanced motion vector prediction (AMVP) mode, and one or more processors in communication with the memory, the one or more processors configured to receive the video data block, construct an affine AMVP motion vector predictor list of candidate control point motion vectors for the video data block, the affine AMVP motion vector predictor list including one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector, determine the control point motion vector for the video data block from the affine AMVP motion vector predictor list, and decode the video data block using the determined control point motion vector.

[0052] In another example of the present disclosure, the video encoder 200 includes a memory configured to store a video data block to be encoded using an affine advanced motion vector prediction (AMVP) mode, and one or more processors in communication with the memory, the one or more processors configured to receive the video data block, construct an affine AMVP motion vector predictor list of candidate control point motion vectors for the video data block, the affine AMVP motion vector predictor list including one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector, determine the control point motion vector for the video data block from the affine AMVP motion vector predictor list, and encode the video data block using the determined control point motion vector.

[0053] The video encoder 200 and the video decoder 300 can operate according to a video code standard (such as ITU-TH.265, also known as high-efficiency video coding (HEVC)) or an extension thereof (such as multi-view and / or scalable video coding extension). Alternatively, the video encoder 200 and the video decoder 300 can operate according to other proprietary or industrial standards, such as the Joint Exploration Test Model (JEM). Recently, the Joint Video Experts Group (JVET) of the Video Coding Experts Group (VCEG) and the Moving Picture Experts Group (MPEG) is developing a new video coding standard called the Versatile Video Coding (VVC) standard. An early draft of VVC is provided in the document JVET-J1001 "Versatile Video Coding (Draft 1)" by Benjamin Bross, and its algorithm description can be obtained in the document JVET-J1002 "Algorithm Description of Versatile Video Coding and Test Model 1 (VTM 1)" by Jianle Chen and Elena Alshina. However, the technology disclosed herein is not limited to any particular coding standard.

[0054] Generally, the video encoder 200 and the video decoder 300 can perform block-based decoding of pictures. The term "block" generally refers to a structure that includes data to be processed (e.g., encoded, decoded, or otherwise used in the encoding and / or decoding process). For example, a block may include a two-dimensional matrix of samples of luminance and / or chrominance data. Generally, the video encoder 200 and the video decoder 300 can decode video data represented in a YUV (e.g., Y, Cb, Cr) format. That is, the video encoder 200 and the video decoder 300 can decode luminance and chrominance components, where the chrominance components may include red and blue chrominance components, instead of decoding red, green, and blue (RGB) data of samples of the picture. In some examples, the video encoder 200 converts the received RGB format data into a YUV representation before encoding, and the video decoder 300 converts the YUV representation into an RGB format. Alternatively, a pre-processing and post-processing unit (not shown) can perform these conversions.

[0055] The present disclosure generally refers to the decoding (e.g., encoding and decoding) of a picture, including the process of encoding or decoding the picture data. Similarly, the present disclosure may refer to the decoding of a block of a picture to include the process of encoding or decoding the data of the block, such as prediction and / or residual decoding. The encoded video bitstream generally includes syntax elements for representing decoding decisions (e.g., decoding modes) and a series of values ​​for partitioning the picture into blocks. Thus, references to decoding a picture or a block should generally be understood as decoding the values ​​of the syntax elements that form the picture or block.

[0056] HEVC defines various blocks, including coding units (CU), prediction units (PU), and transform units (TU). According to HEVC, a video decoder (such as video encoder 200) divides a coding tree unit (CTU) into CUs according to a quadtree structure. That is, the video decoder divides the CTU and CU into four equal non-overlapping squares, and each node of the quadtree has zero or four child nodes. A node without a child node may be referred to as a "leaf node", and the CU of such a leaf node may include one or more PUs and / or one or more TUs. The video decoder may further divide the PU and TU. For example, in HEVC, the residual quadtree (RQT) represents the division of the TU. In HEVC, PU represents inter-frame prediction data, and TU represents residual data. The intra-predicted CU includes intra-frame prediction information, such as an intra-frame mode indication.

[0057] As another example, the video encoder 200 and the video decoder 300 can be configured to operate according to JEM and / or VVC. According to some examples of JEM and / or VVC, a video decoder (such as the video encoder 200) partitions a picture into multiple coding tree units (CTUs). The video encoder 200 can partition the CTU according to a tree structure such as a quadtree-binary tree (QTBT) structure. The QTBT structure of JEM eliminates the concept of multiple partition types, such as the distinction between CU, PU, ​​and TU of HEVC. The QTBT structure of JEM / VCC includes two levels: a first level partitioned according to quadtree partitioning, and a second level partitioned according to binary tree partitioning. The root node of the QTBT structure corresponds to the CTU. The leaf nodes of the binary tree correspond to coding units (CUs).

[0058] In some examples, the video encoder 200 and the video decoder 300 may use a single QTBT structure to represent each of the luma component and the chroma components, while in other examples, the video encoder 200 and the video decoder 300 may use two or more QTBT structures, such as one QTBT structure for the luma component and another QTBT structure for the two chroma components (or two QTBT structures for respective chroma components).

[0059] The video encoder 200 and the video decoder 300 may be configured to use quadtree segmentation according to HEVC, QTBT segmentation of JEM / VCC, or other segmentation structures. For illustrative purposes, a description of the technology of the present disclosure is given for QTBT segmentation. However, it should be understood that the technology of the present disclosure may also be applied to a video decoder configured to use quadtree segmentation or other types of segmentation.

[0060] The present disclosure may use "N×N" and "N by N" interchangeably to represent the sample dimensions of a block (such as a CU or other video block) in the vertical and horizontal dimensions, for example, 16×16 samples or 16 by 16 samples. Generally, a 16×16 CU will have 16 samples in the vertical direction (y=16) and 16 samples in the horizontal direction (x=16). Similarly, an N×N CU generally has N samples in the vertical direction and N samples in the horizontal direction, where N represents a non-negative integer value. The samples in a CU may be arranged in rows and columns. In addition, a CU does not necessarily have the same number of samples in the horizontal direction as in the vertical direction. For example, a CU may contain N×M samples, where M is not necessarily equal to N.

[0061] The video encoder 200 encodes the video data of the CU representing the prediction and / or residual information and other information. The prediction information indicates how the CU will be predicted in order to form a prediction block for the CU. The residual information generally represents the sample-by-sample difference between the samples of the CU before encoding and the prediction block.

[0062] In order to predict a CU, the video encoder 200 can generally form a prediction block for the CU by inter-frame prediction or intra-frame prediction. Inter-frame prediction generally refers to predicting a CU from data of a previously decoded picture, while intra-frame prediction generally refers to predicting a CU from previously decoded data of the same picture. In order to perform inter-frame prediction, the video encoder 200 can use one or more motion vectors to generate a prediction block. The video encoder 200 can generally perform a motion search to identify a reference block that closely matches the CU, for example, in terms of the difference between the CU and the reference block. The video encoder 200 can use the sum of absolute differences (SAD), the sum of squared differences (SSD), the mean absolute difference (MAD), the mean square difference (MSD), or other such difference calculations to calculate a difference metric to determine whether the reference block closely matches the current CU. In some examples, the video encoder 200 can use unidirectional prediction or bidirectional prediction to predict the current CU.

[0063] Examples of JEM and VVC may also provide an affine motion compensation mode, which may be considered an inter-frame prediction mode. In the affine motion compensation mode, the video encoder 200 may determine two or more motion vectors representing non-translational motion, such as zooming in or out, rotation, perspective motion, or other irregular motion types. This disclosure describes techniques related to affine motion prediction in more detail below.

[0064] To perform intra prediction, the video encoder 200 may select an intra prediction mode to generate a prediction block. The examples of JEM and VVC provide sixty-seven intra prediction modes, including modes of various directions as well as a plane mode and a DC mode. Generally, the video encoder 200 selects an intra prediction mode that describes neighboring samples of a current block (e.g., a block of a CU) from which to predict the prediction samples of the current block. Assuming that the video encoder 200 decodes CTUs and CUs in a raster scan order (from left to right, from top to bottom), such samples may typically be above, to the left of, or to the left of the current block in the same picture as the current block.

[0065] The video encoder 200 encodes data representing the prediction mode of the current block. For example, for inter-frame prediction mode, the video encoder 200 can encode data representing which of the various available inter-frame prediction modes is used and the motion information of the corresponding mode. For unidirectional or bidirectional inter-frame prediction, for example, the video encoder 200 can encode the motion vector using advanced motion vector prediction (AMVP) or merge mode. The video encoder 200 can use a similar mode to encode the motion vector of the affine motion compensation mode.

[0066] After prediction (such as intra-frame prediction or inter-frame prediction of a block), the video encoder 200 can calculate residual data for the block. The residual data (such as a residual block) represents the sample-by-sample difference between the block and a prediction block for the block, which is formed using a corresponding prediction mode. The video encoder 200 can apply one or more transforms to the residual block to generate transform data in a transform domain rather than a sample domain. For example, the video encoder 200 can apply a discrete cosine transform (DCT), an integer transform, a wavelet transform, or a conceptually similar transform to the residual video data. In addition, the video encoder 200 can apply a secondary transform after a primary transform, such as a mode-dependent non-separable secondary transform (MDNSST), a signal-dependent transform, a Karhunen-Loeve transform (KLT), etc. The video encoder 200 generates transform coefficients after applying one or more transforms.

[0067] As described above, after performing any transforms to produce transform coefficients, the video encoder 200 can perform quantization on the transform coefficients. Quantization generally refers to the process of quantizing the transform coefficients to possibly reduce the amount of data used to represent the coefficients, thereby providing further compression. By performing the quantization process, the video encoder 200 can reduce the bit depth associated with some or all of the coefficients. For example, the video encoder 200 can round an n-bit value to an m-bit value during quantization, where n is greater than m. In some examples, to perform quantization, the video encoder 200 can perform a bitwise right shift on the value to be quantized.

[0068] After quantization, the video encoder 200 can scan the transform coefficients to generate a one-dimensional vector from a two-dimensional matrix including the quantized transform coefficients. The scan can be designed to place coefficients with higher energy (and therefore lower frequency) in front of the vector and transform coefficients with lower energy (and therefore higher frequency) in the back of the vector. In some examples, the video encoder 200 can scan the quantized transform coefficients using a predefined scan order to generate a serialized vector, and then entropy encode the quantized transform coefficients of the vector. In other examples, the video encoder 200 can perform adaptive scanning. After scanning the quantized transform coefficients to form a one-dimensional vector, the video encoder 200 can entropy encode the one-dimensional vector, for example, according to context adaptive binary arithmetic coding (CABAC). The video encoder 200 can also entropy encode values ​​for syntax elements that describe metadata associated with the encoded video data used by the video decoder 300 in decoding the video data.

[0069] To perform CABAC, the video encoder 200 may assign context within a context model to a symbol to be transmitted. For example, the context may relate to whether the neighboring values ​​of the symbol are zero values. The probability determination may be based on the context assigned to the symbol.

[0070] The video encoder 200 may further generate syntax data, such as block-based syntax data, picture-based syntax data, and sequence-based syntax data, to the video decoder 300, for example, in a picture header, a block header, a slice header, or generate other syntax data, such as a sequence parameter set (SPS), a picture parameter set (PPS), or a video parameter set (VPS). The video decoder 300 may similarly decode such syntax data to determine how to decode the corresponding video data.

[0071] In this way, the video encoder 200 can generate a bitstream including encoded video data, such as syntax elements describing the partitioning of a picture into blocks (eg, CUs) and prediction and / or residual information for the blocks. Finally, the video decoder 300 can receive the bitstream and decode the encoded video data.

[0072] In general, the video decoder 300 performs the reverse process performed by the video encoder 200 to decode the encoded video data of the bitstream. For example, the video decoder 300 may use CABAC to decode the values ​​of the syntax elements of the bitstream in a manner substantially similar to (although reversed from) the CABAC encoding process of the video encoder 200. The syntax elements may define partitioning information regarding partitioning of a picture into CTUs and partitioning each CTU according to a corresponding partitioning structure, such as a QTBT structure, to define CUs of the CTU. The syntax elements may further define prediction and residual information for a block (e.g., a CU) of video data.

[0073] For example, the residual information may be represented by quantized transform coefficients. The video decoder 300 may inverse quantize and inverse transform the quantized transform coefficients of the block to reproduce the residual block of the block. The video decoder 300 uses the signaled prediction mode (intra-frame or inter-frame prediction) and related prediction information (e.g., motion information for inter-frame prediction) to form a prediction block for the block. The video decoder 300 may then combine the prediction block and the residual block (on a sample-by-sample basis) to reproduce the original block. The video decoder 300 may perform additional processes (such as performing a deblocking process) to reduce visual artifacts along block boundaries.

[0074] In accordance with the techniques of this disclosure, video encoder 200 and video decoder 300 may be configured to perform any combination of the techniques described below for affine motion prediction.

[0075] In general, the present disclosure may refer to "signaling" certain information, such as syntax elements. The term "signaling" may generally refer to the communication of values ​​for syntax elements and / or other data used to decode encoded video data. That is, the video encoder 200 may signal the values ​​of syntax elements in a bitstream. In general, signaling refers to generating values ​​in a bitstream. As described above, the source device 102 may transmit the bitstream to the target device 116 in substantially real time (or non-real time, such as may occur when storing syntax elements to the storage device 112 for later retrieval by the target device 116).

[0076] Figure 2A and 2B 1 is a conceptual diagram of an example quadtree binary tree (QTBT) structure 130 and a corresponding coding tree unit (CTU) 132. Solid lines represent quadtree partitions and dashed lines indicate binary tree partitions. In each partition (i.e., non-leaf) node of the binary tree, a flag is signaled to indicate which partition type (i.e., horizontal or vertical) is used, where in this example, 0 indicates horizontal partitioning and 1 indicates vertical partitioning. For quadtree partitioning, since the quadtree node divides the block horizontally and vertically into 4 sub-blocks of equal size, there is no need to indicate the partition type. Accordingly, the video encoder 200 can encode syntax elements (e.g., partition information) of the region tree level (i.e., solid line) of the QTBT structure 130 and syntax elements (e.g., partition information) of the prediction tree level (i.e., dashed line) of the QTBT structure 130, and the video decoder 300 can decode the above. For a CU represented by a terminal leaf node of the QTBT structure 130 , the video encoder 200 may encode video data (such as prediction and transform data), and the video decoder 300 may decode the same.

[0077] Generally, Figure 2BThe CTU 132 of the first and second levels may be associated with parameters that define the size of blocks corresponding to nodes of the first and second level QTBT structures 130. These parameters may include a CTU size (representing the size of the CTU 132 in a sample), a minimum quadtree size (MinQTSize, representing the minimum allowed quadtree leaf node size), a maximum binary tree size (MaxBTSize, representing the maximum allowed binary tree root node size), a maximum binary tree depth (MaxBTDepth, representing the maximum allowed binary tree depth), and a minimum binary tree size (MinBTSize, representing the minimum allowed binary tree leaf node size).

[0078] The root node of the QTBT structure corresponding to the CTU can have four child nodes at the first level of the QTBT structure, and each child node can be segmented according to the quadtree segmentation. That is, the node of the first level is a leaf node (no child node) or has four child nodes. The example of the QTBT structure 130 represents such a node, which includes a child node and a parent node with a solid line branch. If the node of the first level is not larger than the maximum allowed binary tree root node size (MaxBTSize), the node can be further segmented by the respective binary trees. The binary tree partitioning of a node can be iterated until the node generated by the partition reaches the minimum allowed binary tree leaf node size (MinBTSize) or the maximum allowed binary tree depth (MaxBTDepth). The example of the QTBT structure 130 represents such a node as having a dotted branch. The binary tree leaf node is represented as a coding unit (CU), which is used for prediction (e.g., intra-picture or inter-picture prediction) and transformation without any further segmentation. As described above, a CU can also be represented as a "video block" or "block".

[0079] In some examples of the QTBT partitioning structure, the CTU size is set to 128×128 (luminance sample and two corresponding 64×64 chroma samples), MinQTSize is set to 16×16, MaxBTSize is set to 64×64, MinBTSize (for width and height) is set to 4, and MaxBTDepth is set to 4. First, quadtree partitioning is applied to the CTU to generate quadtree leaf nodes. Quadtree leaf nodes can have sizes from 16×16 (i.e., MinQTSize) to 128×128 (i.e., CTU size). If the leaf quadtree node is 128×128, since its size exceeds MaxBTSize (64×64 in this example), the leaf quadtree node will not be further divided by the binary tree. Otherwise, the leaf quadtree node will be further divided by the binary tree. Therefore, the quadtree leaf node is also the root node of the binary tree and has a binary tree depth of 0. When the binary tree depth reaches MaxBTDepth (4 in this example), further division is not allowed. When a binary tree node has a width equal to MinBTSize (4 in this example), the binary tree node means that no further horizontal partitioning is allowed. Similarly, a binary tree node with a height equal to MinBTSize indicates that no further vertical partitioning is allowed for the binary tree node. As described above, the leaf nodes of the binary tree are called CUs and are further processed according to prediction and transformation without further segmentation.

[0080] Figure 3 is a block diagram illustrating an example video encoder 200 that may perform the techniques of this disclosure. Figure 3 For purposes of explanation and should not be considered a constraint on the techniques extensively exemplified and described in this disclosure. For purposes of illustration, this disclosure describes the video encoder 200 in the context of video coding standards such as the HEVC video coding standard under development and the H.266 video coding standard (VCC). However, the techniques of this disclosure are not limited to these video coding standards and are generally applicable to video encoding and decoding.

[0081] exist Figure 3 In the example, the video encoder 200 includes a video data memory 230, a mode selection unit 202, a residual generation unit 204, a transform processing unit 206, a quantization unit 208, an inverse quantization unit 210, an inverse transform processing unit 212, a reconstruction unit 214, a filter unit 216, a decoded picture buffer (DPB) 218 ​​and an entropy encoding unit 220.

[0082] The video data memory 230 may store video data to be encoded by the components of the video encoder 200. The video encoder 200 may receive video data from, for example, the video source 104 ( Figure 1) receives video data stored in video data memory 230. DPB 218 can be used as a reference picture memory, which stores reference video data for use by video encoder 200 when predicting subsequent video data. Video data memory 230 and DPB 218 can be formed by any of a variety of storage devices, such as dynamic random access memory (DRAM), including synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM) or other types of storage devices. Video data memory 230 and DPB 218 can be provided by the same storage device or a separate storage device. In various examples, video data memory 230 can be placed on-chip with other components of video encoder 200, as shown, or placed off-chip relative to those components.

[0083] In the present disclosure, references to the video data memory 230 should not be interpreted as limited to a memory inside the video encoder 200 (unless otherwise specified) or a memory outside the video encoder 200 (unless otherwise specified). Of course, references to the video data memory 230 should be understood as a reference memory that stores video data received by the video encoder 200 for encoding (e.g., video data to be encoded of a current block). Figure 1 The memory 106 can also provide temporary storage for the outputs of various units of the video encoder 200 .

[0084] Graphic Figure 3 The various units are used to help understand the operations performed by the video encoder 200. These units can be implemented as fixed-function circuits, programmable circuits, or a combination thereof. Fixed-function circuits refer to circuits that provide specific functions and preset operations that can be performed. Programmable circuits refer to circuits that can be programmed to perform various tasks and provide flexible functions in the operations that can be performed. For example, a programmable circuit can execute software or firmware that causes the programmable circuit to operate in a manner defined by the instructions of the software or firmware. Fixed-function circuits can execute software instructions (for example, to receive parameters or output parameters), but the type of operation performed by the fixed-function circuit is generally immutable. In some examples, one or more units may be different circuit blocks (fixed function or programmable), and in some examples, one or more units may be integrated circuits.

[0085] The video encoder 200 may include an arithmetic logic unit (ALU), an elementary function unit (EFU), a digital circuit, an analog circuit, and / or a programmable core formed by a programmable circuit. In an example where the operation of the video encoder 200 is performed using software executed by a programmable circuit, the memory 106 ( Figure 1) may store instructions (eg, object code) for software received and executed by the video encoder 200, or another memory within the video encoder 200 (not shown) may store such instructions.

[0086] The video data memory 230 is configured to store received video data. The video encoder 200 may retrieve pictures of video data from the video data memory 230 and provide the video data to the residual generation unit 204 and the mode selection unit 202. The video data in the video data memory 230 may be original video data to be encoded.

[0087] The mode selection unit 202 includes a motion estimation unit 222, a motion compensation unit 224, and an intra prediction unit 226. The mode selection unit 202 may include additional functional units for performing video prediction according to other prediction modes. As an example, the mode selection unit 202 may include a palette unit, an intra block copy unit (which may be part of the motion estimation unit 222 and / or the motion compensation unit 224), an affine unit, a linear model (LM) unit, etc.

[0088] Generally, the mode selection unit 202 coordinates multiple encoding times to test a combination of encoding parameters and derive a rate-distortion value for such a combination. The encoding parameters may include a partition of a CTU to a CU, a prediction mode of a CU, a transform type of residual data of a CU, a quantization parameter of residual data of a CU, etc. The mode selection unit 202 may ultimately select a combination of encoding parameters that has a better rate-distortion value than other tested combinations.

[0089] The video encoder 200 may partition the picture retrieved from the video data memory 230 into a series of CTUs and encapsulate one or more CTUs in a slice. The mode selection unit 202 may partition the CTU of the picture according to a tree structure (such as the QTBT structure or quadtree structure of the HEVC described above). As described above, the video encoder 200 may form one or more CUs by partitioning the CTU according to the tree structure. Such a CU may also be generally referred to as a "video block" or "block".

[0090] Generally, the mode selection unit 202 also controls its components (e.g., the motion estimation unit 222, the motion compensation unit 224, and the intra prediction unit 226) to generate a prediction block for a current block (e.g., the overlapping portion of a current CU or a PU and a TU in HEVC). In order to inter-predict the current block, the motion estimation unit 222 may perform a motion search to identify one or more closely matching reference blocks in one or more reference pictures (e.g., one or more previously decoded pictures stored in the DPB 218). In particular, the motion estimation unit 222 may calculate values ​​representing how similar a potential reference block is to the current block based on, for example, the sum of absolute differences (SAD), the sum of squared differences (SSD), the mean absolute difference (MAD), the mean squared difference (MSD), and the like. The motion estimation unit 222 may typically perform these calculations using the sample-by-sample differences between the current block and the reference block under consideration. The motion estimation unit 222 may identify the reference block having the lowest value generated by these calculations, indicating the reference block that most closely matches the current block.

[0091] The motion estimation unit 222 may form one or more motion vectors (MVs) that define the position of a reference block in a reference picture relative to a current block in a current picture. The motion estimation unit 222 may then provide the motion vectors to the motion compensation unit 224. For example, for unidirectional inter prediction, the motion estimation unit 222 may provide a single motion vector, while for bidirectional inter prediction, the motion estimation unit 222 may provide two motion vectors. The motion compensation unit 224 may then use the motion vectors to generate a prediction block. For example, the motion compensation unit 224 may use the motion vectors to retrieve data for the reference block. As another example, if the motion vectors have fractional sample precision, the motion compensation unit 224 may interpolate the prediction block according to one or more interpolation filters. In addition, for bidirectional inter prediction, the motion compensation unit 224 may retrieve data for two reference blocks identified by respective motion vectors and combine the retrieved data (e.g., by sample-by-sample averaging or weighted averaging).

[0092] According to the techniques of the present disclosure, the motion estimation unit 222 and the motion compensation unit 224 can be configured to perform any combination of the techniques described below for affine motion prediction. For example, as will be explained in more detail below, the motion estimation unit 222 and the motion compensation unit 224 can be configured to receive a block of video data to be encoded using an affine advanced motion vector prediction (AMVP) mode, construct an affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, the affine AMVP motion vector predictor list including one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector, determine the control point motion vector for the block of video data from the affine AMVP motion vector predictor list, and encode the block of video data using the determined control point motion vector.

[0093] As another example, for intra prediction or intra prediction decoding, the intra prediction unit 226 may generate a prediction block based on samples adjacent to the current block. For example, for directional mode, the intra prediction unit 226 may generally mathematically combine the values ​​of the adjacent samples and fill these calculated values ​​along a defined direction on the current block to generate a prediction block. As another example, for DC mode, the intra prediction unit 226 may calculate an average value of the adjacent samples of the current block and generate a prediction block to include the average value obtained for each sample of the prediction block.

[0094] The mode selection unit 202 provides the prediction block to the residual generation unit 204. The residual generation unit 204 receives the original uncoded version of the current block from the video data memory 230 and receives the prediction block from the mode selection unit 202. The residual generation unit 204 calculates the sample-by-sample difference between the current block and the prediction block. The resulting sample-by-sample difference defines a residual block for the current block. In some examples, the residual generation unit 204 may also use residual differential pulse code modulation (RDPCM) to determine the difference between the sample values ​​in the residual block to generate the residual block. In some examples, the residual generation unit 204 may be formed using one or more subtractor circuits that perform binary subtraction.

[0095] In the example where the mode selection unit 202 partitions the CU into PUs, each PU may be associated with a luma prediction unit and a corresponding chroma prediction unit. The video encoder 200 and the video decoder 300 may support PUs of various sizes. As described above, the size of the CU may refer to the size of the luma coding block of the CU, and the size of the PU may refer to the size of the luma prediction unit of the PU. Assuming that the size of a particular CU is 2N×2N, the video encoder 200 may support PU sizes of 2N×2N or N×N for intra-frame prediction, and symmetric PU sizes of 2N×2N, 2N×N, N×2N, N×N or similar for inter-frame prediction. The video encoder 20 and the video decoder 30 may also support asymmetric partitioning of PU sizes of 2N×nU, 2N×nD, nL×2N and nR×2N for inter-frame prediction.

[0096] In an example where the mode selection unit does not further split the CU into PUs, each CU may be associated with a luma coding block and a corresponding chroma coding block. As described above, the size of a CU may refer to the size of the luma coding block of the CU. The video encoder 200 and the video decoder 300 may support a CU size of 2N×2N, 2N×N, or N×2N.

[0097] For other video coding techniques, such as intra block copy mode coding, affine mode coding, and linear model (LM) mode coding as some examples, the mode selection unit 202 generates a prediction block for the current block being encoded via respective units associated with the coding techniques. In some examples, such as palette mode coding, the mode selection unit 202 may not generate a prediction block, but may generate syntax elements indicating how to reconstruct the block based on the selected palette. In such a mode, the mode selection unit 202 may provide these syntax elements to the entropy coding unit 220 for encoding.

[0098] As described above, the residual generation unit 204 receives video data of a current block and a corresponding prediction block. Then, the residual generation unit 204 generates a residual block for the current block. To generate the residual block, the residual generation unit 204 calculates the sample-by-sample difference between the prediction block and the current block.

[0099] The transform processing unit 206 applies one or more transforms to the residual block to generate a block of transform coefficients (referred to herein as a "transform coefficient block"). The transform processing unit 206 can apply various transforms to the residual block to form a transform coefficient block. For example, the transform processing unit 206 can apply a discrete cosine transform (DCT), a directional transform, a Karhunen-Loeve transform (KLT), or a conceptually similar transform to the residual block. In some examples, the transform processing unit 206 can perform multiple transforms on the residual block, for example, a primary transform and a secondary transform such as a rotation transform. In some examples, the transform processing unit 206 does not apply a transform to the residual block.

[0100] The quantization unit 208 may quantize the transform coefficients in the transform coefficient block to produce a quantized transform coefficient block. The quantization unit 208 may quantize the transform coefficients of the transform coefficient block according to a quantization parameter (QP) value associated with the current block. The video encoder 200 (e.g., via the mode selection unit 202) may adjust the degree of quantization applied to the transform coefficient block associated with the current block by adjusting the QP value associated with the CU. Quantization may introduce information loss, and thus, the quantized transform coefficients may have lower precision than the original transform coefficients produced by the transform processing unit 206.

[0101] The inverse quantization unit 210 and the inverse transform processing unit 212 may apply inverse quantization and inverse transform, respectively, to the quantized transform coefficient block to reconstruct a residual block from the transform coefficient block. The reconstruction unit 214 may generate a reconstructed block corresponding to the current block (although potentially with some degree of distortion) based on the reconstructed residual block and the prediction block generated by the mode selection unit 202. For example, the reconstruction unit 214 may add samples of the reconstructed residual block to corresponding samples of the prediction block generated by the mode selection unit 202 to generate a reconstructed block.

[0102] Filter unit 216 may perform one or more filter operations on the reconstructed block. For example, filter unit 216 may perform a deblocking operation to reduce blocking artifacts along the edge of the CU. In some examples, the operation of filter unit 216 may be skipped.

[0103] The video encoder 200 stores the reconstructed blocks in the DPB 218. For example, in an example where the operation of the filter unit 216 is not required, the reconstruction unit 214 can store the reconstructed blocks to the DPB 218. In an example where the operation of the filter unit 216 is required, the filter unit 216 can store the filtered reconstructed blocks to the DPB 218. The motion estimation unit 222 and the motion compensation unit 224 can retrieve a reference picture from the DPB 218, which is formed by the reconstructed (and potentially filtered) blocks, to perform inter-frame prediction on blocks of subsequently encoded pictures. In addition, the intra-frame prediction unit 226 can use the reconstructed blocks in the DPB 218 of the current picture to perform intra-frame prediction on other blocks in the current picture.

[0104] In general, the entropy coding unit 220 may entropy encode syntax elements received from other functional components of the video encoder 200. For example, the entropy coding unit 220 may entropy encode a block of quantized transform coefficients from the quantization unit 208. As another example, the entropy coding unit 220 may entropy encode a prediction syntax element (e.g., motion information for inter-frame prediction or intra-frame mode information for intra-frame prediction) from the mode selection unit 202. The entropy coding unit 220 may perform one or more entropy coding operations on syntax elements of another example of video data to generate entropy-encoded data. For example, the entropy coding unit 220 may perform a context-adaptive variable length coding (CAVLC) operation, a CABAC operation, a variable to variable (V2V) length coding operation, a syntax-based context-adaptive binary arithmetic coding (SBAC) operation, a probability interval partitioning entropy (PIPE) coding operation, an exponential-Grund coding operation, or another type of entropy coding operation on the data. In some examples, the entropy coding unit 220 may operate in a bypass mode when the syntax element is not entropy encoded.

[0105] The video encoder 200 may output a bitstream including entropy coding syntax elements required to reconstruct blocks of a slice or picture. In particular, the entropy coding unit 220 may output a bitstream.

[0106] The above operations are described for blocks. Such descriptions should be understood as operations for luma coding blocks and / or chroma coding blocks. As described above, in some examples, the luma coding block and the chroma coding block are the luma and chroma components of the CU. In some examples, the luma coding block and the chroma coding block are the luma and chroma components of the PU.

[0107] In some examples, the operations performed for the luma coding block do not need to be repeated for the chroma coding block. As an example, the operations for identifying the motion vector (MV) and reference picture for the luma coding block do not need to be repeated to identify the MV and reference picture for the chroma block. Instead, the MV of the luma coding block may be scaled to determine the MV of the chroma block, and the reference picture may be the same. As another example, the intra prediction process may be the same for the luma coding block and the chroma coding block.

[0108] The video encoder 200 represents an example of a device configured to encode video data, the device including a memory configured to store the video data, and one or more processing units implemented in circuitry configured to perform any combination of the techniques described below for affine motion prediction. As an example, the video encoder 200 may be configured to receive a block of video data to be encoded using an affine advanced motion vector prediction (AMVP) mode, construct an affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, the affine AMVP motion vector predictor list including one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector, determine a control point motion vector for the block of video data from the affine AMVP motion vector predictor list, and encode the block of video data using the determined control point motion vector.

[0109] Figure 4 is a block diagram illustrating an example video decoder 300 that may perform the techniques of this disclosure. Figure 4 The techniques widely exemplified and described in this disclosure are for the purpose of explanation, not limitation. For the purpose of illustration, this disclosure describes a video decoder 300 according to the technical description of JEM / VCC and HEVC. However, the techniques of this disclosure may be performed by video decoding devices configured for other video decoding standards.

[0110] exist Figure 4 In the example of , the video decoder 300 includes a coded picture buffer (CPB) memory 320, an entropy decoding unit 302, a prediction processing unit 304, an inverse quantization unit 306, an inverse transform processing unit 308, a reconstruction unit 310, a filter unit 312, and a decoded picture buffer (DPB) 314. The prediction processing unit 304 includes a motion compensation unit 316 and an intra prediction unit 318. The prediction processing unit 304 may include additional units to perform predictions according to other prediction modes. As an example, the prediction processing unit 304 may include a palette unit, an intra block copy unit (which may form part of the motion compensation unit 316), an affine unit, a linear model (LM) unit, etc. In other examples, the video decoder 300 may include more, fewer, or different functional components.

[0111] CPB memory 320 may store video data, such as an encoded video bitstream, to be decoded by components of video decoder 300. For example, the video bitstream may be obtained from computer readable medium 110 ( Figure 1 ) obtains video data stored in CPB memory 320. CPB memory 320 may include a CPB that stores coded video data (e.g., syntax elements) from a coded video bitstream. Moreover, CPB memory 320 may store video data other than syntax elements of decoded pictures, such as temporary data representing outputs from various units of video decoder 300. Generally, DPB 314 stores decoded pictures, and video decoder 300 may output decoded pictures and / or use them as reference video data when decoding subsequent data or pictures of the coded video bitstream. CPB memory 320 and DPB 314 may be formed by any of a variety of storage devices, such as dynamic random access memory (DRAM), including synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of storage devices. CPB memory 320 and DPB 314 may be provided by the same storage device or a separate storage device. In various examples, CPB memory 320 may be placed on-chip with other components of video decoder 300, or placed off-chip relative to those components.

[0112] Additionally or alternatively, in some examples, video decoder 300 may retrieve the video from memory 120 ( Figure 1 ) to retrieve the decoded video data. That is, memory 120 may store data together with CPB memory 320 as discussed above. Similarly, when some or all of the functions of video decoder 300 are implemented in software to be executed by the processing circuitry of video decoder 300, memory 120 may store instructions to be executed by video decoder 300.

[0113] Graphics Figure 4 Various units are shown to aid in understanding the operations performed by the video decoder 300. These units may be implemented as fixed function circuits, programmable circuits, or a combination thereof. Figure 3, fixed-function circuits refer to circuits that provide specific functions and are preset in the operations that can be performed. Programmable circuits refer to circuits that can be programmed to perform various tasks and provide flexible functions in the operations that can be performed. For example, a programmable circuit can execute software or firmware that causes the programmable circuit to operate in a manner defined by the instructions of the software or firmware. Fixed-function circuits can execute software instructions (for example, to receive parameters or output parameters), but the type of operation performed by the fixed-function circuit is generally immutable. In some examples, one or more of the units may be different circuit blocks (fixed function or programmable), and in some examples, one or more units may be integrated circuits.

[0114] The video decoder 300 may include an ALU, an EFU, a digital circuit, an analog circuit, and / or a programmable core formed by a programmable circuit. In an example where the operation of the video decoder 300 is performed by software executed on a programmable circuit, an on-chip or off-chip memory may store instructions (e.g., object code) of the software received and executed by the video decoder 300.

[0115] The entropy decoding unit 302 may receive the encoded video data from the CPB and entropy decode the video data to reproduce the syntax elements. The prediction processing unit 304, the inverse quantization unit 306, the inverse transform processing unit 308, the reconstruction unit 310, and the filter unit 312 may generate decoded video data based on the syntax elements extracted from the bitstream.

[0116] Generally, the video decoder 300 reconstructs a picture on a block-by-block basis. The video decoder 300 may perform a reconstruction operation on each block individually (where the block currently being reconstructed (ie, decoded) may be referred to as a "current block").

[0117] The entropy decoding unit 302 may entropy decode syntax elements defining quantized transform coefficients of the quantized transform coefficient block and transform information such as a quantization parameter (QP) and / or a transform mode indication. The inverse quantization unit 306 may use the QP associated with the quantized transform coefficient block to determine a degree of quantization, and likewise, determine a degree of inverse quantization for the inverse quantization unit 306 to apply. The inverse quantization unit 306 may inverse quantize the quantized transform coefficients (e.g., by performing a bitwise left shift operation). The inverse quantization unit 306 may thereby form a transform coefficient block including the transform coefficients.

[0118] After the inverse quantization unit 306 forms the transform coefficient block, the inverse transform processing unit 308 may apply one or more inverse transforms to the transform coefficient block to generate a residual block associated with the current block. For example, the inverse transform processing unit 308 may apply an inverse DCT, an inverse integer transform, an inverse Karhunen-Loeve transform (KLT), an inverse rotational transform, an inverse directional transform, or another inverse transform to the transform coefficient block.

[0119] Further, prediction processing unit 304 generates a prediction block based on the prediction information syntax element entropy decoded by entropy decoding unit 302. For example, if the prediction information syntax element indicates that the current block is inter-predicted, motion compensation unit 316 may generate the prediction block. In this case, the prediction information syntax element may indicate a reference picture in DPB 314 from which to retrieve the reference block, and a motion vector that identifies the position of the reference block in the reference picture relative to the current block in the current picture. Motion compensation unit 316 may generally generate a prediction block in the same manner as for motion compensation unit 224 ( Figure 3 ) in a manner substantially similar to that described in the foregoing description. According to the techniques of the present disclosure, the motion compensation unit 316 may be configured to perform any combination of the techniques described below for affine motion prediction. For example, the motion compensation unit 316 may be configured to receive a video data block encoded using an affine advanced motion vector prediction (AMVP) mode, construct an affine AMVP motion vector predictor list of candidate control point motion vectors for the video data block, the affine AMVP motion vector predictor list including one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector, determine the control point motion vector for the video data block from the affine AMVP motion vector predictor list, and decode the video data block using the determined control point motion vector.

[0120] As another example, if the prediction information syntax element indicates that the current block is intra-predicted, the intra-prediction unit 318 may generate a prediction block according to the intra-prediction mode indicated by the prediction information syntax element. Again, the intra-prediction unit 318 may generally generate a prediction block in the same manner as for the intra-prediction unit 226 ( Figure 3 The intra prediction process is performed in a manner substantially similar to that described in the description of FIG. 314. The intra prediction unit 318 may retrieve data of neighboring samples of the current block from the DPB 314.

[0121] The reconstruction unit 310 may reconstruct the current block using the prediction block and the residual block. For example, the reconstruction unit 310 may add samples of the residual block to corresponding samples of the prediction block to reconstruct the current block.

[0122] The filter unit 312 may perform one or more filter operations on the reconstructed block. For example, the filter unit 312 may perform a deblocking operation to reduce blocking artifacts along the edges of the reconstructed block. The operations of the filter unit 312 may not necessarily be performed in all examples.

[0123] The video decoder 300 may store the reconstructed blocks in the DPB 314. As described above, the DPB 314 may provide reference information to the prediction processing unit 304, such as samples of the current picture for intra prediction and previously decoded pictures for subsequent motion compensation. In addition, the video decoder 300 may output decoded pictures from the DPB 314 for subsequent presentation on, for example, Figure 1 on a display device 118 of the display device.

[0124] In this manner, the video decoder 300 represents an example of a video decoding device that includes a memory configured to store video data and implemented in circuitry and configured to perform any combination of the techniques described below for affine motion prediction. As will be explained in more detail below, the video decoder 300 can be configured to receive a block of video data encoded using an affine advanced motion vector prediction (AMVP) mode, construct an affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, the affine AMVP motion vector predictor list including one or more affine motion vector predictors that cause all control point motion vectors to be equal to a specified motion vector, determine a control point motion vector for the block of video data from the affine AMVP motion vector predictor list, and decode the block of video data using the determined control point motion vector.

[0125] In this section, we will describe the affine motion model. The affine motion model can be described as:

[0126]

[0127] Among them, (v x , v y ) is the motion vector at the coordinate (x, y), and a, b, c, d, e, and f are six parameters of the affine motion model. The affine motion model for the block can also be obtained by three motion vectors at the three corners of the block 500: and (also called control point motion vector), such as Figure 5 The playground is described as:

[0128]

[0129] Wherein, w and h are the width and height of the block 500. The above affine motion model may be referred to as a 6-parameter affine motion model.

[0130] The simplified 4-parameter affine motion model is described as:

[0131]

[0132] Similarly, a simplified 4-parameter affine motion model for a block can be obtained by using the two control point motion vectors at the two corners of block 510: and To describe, such as Figure 6 The sports field is described as:

[0133]

[0134] Techniques for other control point motion vector selection techniques will now be described. The control point motion vectors are not necessarily Figure 5 or Figure 6 Other control point motion vector selection techniques may also be used. For a 4-parameter affine motion model, the video encoder 200 and / or the video decoder 300 may be configured to select the control point motion vector from the control point motion vector. Any two pairs of control points in Figure 6 As shown in . For the 6-parameter affine motion model, the video encoder 200 and / or the video decoder 300 can be configured to select a control point pair from any three of the control point motion vectors. Given the selected control point motion vectors, the video encoder 200 and / or the video decoder 300 can be configured to calculate other motion vectors through the derived affine motion model.

[0135] As in the motion vector prediction techniques in HEVC, the affine motion predictor can be derived from the affine motion vectors or standard (eg, translation) motion vectors of neighboring coding blocks. Two example types of affine motion predictors include inherited affine motion vector predictors and constructed affine motion vector predictors.

[0136] To determine the inherited affine motion vector predictor, the video encoder 200 and / or the video decoder 300 uses the affine motion model of the candidate block to derive the prediction motion vector at the control point of the current block. It is assumed that the current block shares the same affine motion model with the candidate block. Figure 7 An example for the current block 520 is shown in FIG. The affine motion vector of the candidate block A 530 (expressed as the motion vector at the control point) is and The size of candidate block A 530 is (w, h), and the coordinates of the control points of candidate block A 530 are (x0, y0), (x1, y1), and (x2, y2). The video encoder 200 and / or the video decoder 300 may be configured to derive the predicted affine motion vector at the control point of the current block 520 by replacing (x, y) in equation (2) with the coordinate difference between the control point of the current block 520 and the upper left control point of the candidate block A 530. and

[0137]

[0138]

[0139]

[0140] Among them, (x0′, y0′), (x1′, y1′), and (x2′, y2′) are the coordinates of the control points in the current block 520 .

[0141] Similarly, if the affine motion model for the candidate block is a 4-parameter affine motion model, the video encoder 200 and / or the video decoder 300 may be configured to apply equation (4). If the affine motion model for the current block is a 4-parameter affine motion model, equation (6) may be ignored.

[0142] In the above example, candidate block A 530 may be located at different locations, such as Figure 8 Position A0, B0, B1, A1 or B2 as shown in .

[0143] The constructed affine motion vector predictor will now be described. The video encoder 200 and / or the video decoder 300 may be configured to derive the constructed affine motion vector predictor by predicting the motion vector at the control point of the current block, as in standard motion vector prediction. For example, Figure 8 As shown in , the control point motion vector at the upper left control point The control point motion vector at the top right control point can be predicted by the standard (e.g., translation) motion vector at B2, B3, or A2. can be predicted by a standard (eg, translation) motion vector at B0 or ​​B1, and the control point motion vector at the lower left control point It can be predicted by a standard (eg translational) motion vector at A0 or A1.

[0144] An example of pruning of an affine motion vector predictor will now be described. In order to remove duplicate affine motion vector predictors, the video encoder 200 and / or the video decoder 300 may be configured to apply a pruning process. When comparing two affine motion vector predictors, the video encoder 200 and / or the video decoder 300 may be configured to compare the motion vectors at the control points. In the case of multiple reference frames, the video encoder 200 and / or the video decoder 300 may be configured to also compare reference indices. In the case of bidirectional prediction, the video encoder 200 and / or the video decoder 300 may be configured to compare the following two: the motion vectors at the control points and the reference indices for the two prediction directions.

[0145] This disclosure describes techniques for performing affine motion prediction. The video encoder 200 and the video decoder 300 may be configured to independently perform any of the following techniques. Additionally, the video encoder 200 and the video decoder 300 may be configured to perform the following techniques in any combination.

[0146] In some examples, the present disclosure describes simplified pruning techniques for an affine motion vector predictor. In some examples, the video encoder 200 and / or the video decoder 300 may be configured to compare only one motion vector at a specified control point during the pruning process, rather than comparing motion vectors at all control points. In one example, the specified control point is the top left control point. The video encoder 200 and / or the video decoder 300 may be configured to compare the control point motion vectors of the new affine motion vector predictor if The control point motion vector that matches any existing affine motion vector predictor in the affine motion vector predictor list If they are the same, the new predictor is discarded.

[0147] In another example, the designated control point is the top right control point. The video encoder 200 and / or the video decoder 300 may be configured to if the control point motion vector of the new affine motion vector predictor The control point motion vector that matches any existing affine motion vector predictor in the affine motion vector predictor list If they are the same, the new predictor is discarded.

[0148] In yet another example, the designated control point is the lower left control point. The video encoder 200 and / or the video decoder 300 may be configured to if the control point motion vector of the new affine motion vector predictor The control point motion vector that matches any existing affine motion vector predictor in the affine motion vector predictor list If the new predictor is the same, the new predictor is discarded. Note that during the comparison, reference indices may also be compared if available.

[0149] In another example, the pruning process may depend on the type of affine motion vector predictor. For example, if the new affine motion vector predictor is an inherited affine motion vector predictor, the video encoder 200 and / or the video decoder 300 may be configured to compare only one motion vector at a specified control point. If the new affine motion vector predictor is a constructed affine motion vector predictor, the video encoder 200 and / or the video decoder 300 may be configured not to apply the pruning process.

[0150] In another example, this disclosure describes techniques that may allow line buffer reduction for inherited affine motion vector prediction.Since the motion information predictor is derived from the reconstructed motion information of the previously reconstructed block, the motion parameters from the previously reconstructed block are stored in a motion parameter buffer.

[0151] In a typical decoder design, a working buffer is used to store reconstructed data, such as pixel values, decoding information (e.g., skip mode, prediction mode, merge mode), and also stores reconstructed motion information (e.g., reference picture index, motion vector) for a predefined working block size (e.g., CTU or largest coding unit (LCU)). Typically, the working buffer uses a local memory with very low access latency, such as a cache, on-chip memory. For simplicity, in the following context of the present disclosure, the working block size is assumed to be the CTU size. For each block within a CTU, if the predictive decoding information is derived from a neighboring block within the same CTU, the video decoder 300 only needs to extract the data stored in the working buffer. However, when the predictive decoding information is derived from a block outside the CTU to which the current block belongs, the prediction information must be extracted from a buffer outside the working buffer, which may result in longer delays. To address this problem, a row buffer is used to avoid longer access delays.

[0152] The line buffer is a local memory with low access latency and is used to store prediction decoding information of blocks outside the current working block (e.g., working CTU), and the stored information is usually used for spatial prediction of the next block. It is common practice that when high-resolution video is involved, CTUs are encoded / decoded in raster scan order, and reconstructed samples and other decoding information are usually written to a remote / non-local storage area (e.g., DDRSRAM) after decoding the CTU, which can free up local memory (usually of very limited size compared to the video data) for encoding / decoding of subsequent CTUs.

[0153] When starting to encode / decode the second CTU row forward, the reconstructed samples and other decoding information from the bottom of the previous CTU row are reloaded into the local memory so that the data from the upper CTU can be used as soon as the computing unit needs them in the encoding / decoding process. Fig. 9 As shown in , in a typical HEVC implementation, a line buffer is used to store motion information of one line of 4x4 blocks over the picture width plus one CTU height for spatial motion vector (MV) prediction.

[0154] For the inherited affine motion vector predictor, if the neighboring candidate blocks are located outside the current CTU, an additional line buffer may be beneficial in order to store the motion vectors at all control points. Fig.10 As illustrated in , if the neighboring block is located outside the current CTU of the current block, an additional buffer is used to store the upper left control point motion information and the upper right control point motion information.

[0155] In order to reduce the additional line buffer for the inherited affine motion vector predictor, the video encoder 200 and / or the video decoder 300 may be configured to derive the predictor using only the control point motion vectors stored in the original line buffer. For example, if the neighboring block is located in the upper CTU, a 4-parameter affine motion model is assumed for the neighboring block regardless of its actual affine motion model, and the video encoder 200 and / or the video decoder 300 may be configured to derive the affine motion model for the neighboring block using the lower left control point MV and the lower right control point MV, and then derive the predictor. If the neighboring block is located in the left CTU, a 4-parameter affine motion model is also assumed for the neighboring block regardless of its actual affine motion model, and the video encoder 200 and / or the video decoder 300 may be configured to derive the affine motion model for the neighboring block using the upper right control point MV and the lower right control point MV, and then derive the predictor.

[0156] In another example, the video encoder 200 and / or the video decoder 300 may be configured to store a limited number of upper left control points MV in an additional line buffer. The video encoder 200 and / or the video decoder 300 may be configured to use a flag in the line buffer to indicate whether the upper left control point MV of the 6-parameter affine neighboring block is stored in the additional line buffer. If the neighboring block is located in the upper CTU, it is decoded using the 6-parameter affine motion model, and the flag is true, the video encoder 200 and / or the video decoder 300 may be configured to use the stored upper left control point MV and the lower left and lower right control point MVs to derive the affine motion model, and then derive the predictor. If the neighboring block is located in the left CTU, it is decoded using the encoded 6-parameter affine motion model, and the flag is true, the video encoder 200 and / or the video decoder 300 may be configured to use the stored upper left control point MV and the upper right and lower right control point MVs to derive the affine motion model, and then derive the predictor. If the flag is false, the 6-parameter affine motion model is considered to be a 4-parameter affine motion model. In this case, the video encoder 200 and / or the video decoder 300 may be configured to derive the affine motion model using the two control points MV stored in the original line buffer and then derive the predictor.

[0157] In one example, the finite number of upper left control points MV in the additional line buffer can be 1 or other integers. For the upper CTU, the upper left control point MV to be stored can be selected by selecting the 6-parameter affine motion model block in the bottom boundary of the upper CTU with the minimum X coordinate. For the left CTU, the upper left control point MV to be stored can be selected by selecting the 6-parameter affine motion model block in the right boundary of the left CTU with the minimum Y coordinate.

[0158] In another example, the finite number of upper left control points MV in the additional line buffer can be 1 or other integers. For the upper CTU, the upper left control point MV to be stored can be selected by selecting the 6-parameter affine motion model block in the bottom boundary of the upper CTU with the maximum X coordinate. For the left CTU, the upper left control point MV to be stored can be selected by selecting the 6-parameter affine motion model block in the right boundary of the left CTU with the maximum Y coordinate.

[0159] In another example, the finite number of upper left control points MV in the additional line buffer can be 1 or other integers. For the upper CTU, the upper left control point MV to be stored can be selected by selecting a 6-parameter affine motion model block located in the middle of the bottom boundary of the upper CTU. If the block located in the middle of the bottom boundary of the upper CTU is not affine motion decoded, the upper left control point MV is considered unavailable. For the left CTU, the upper left control point MV to be stored can be selected by selecting a 6-parameter affine motion model block located in the middle of the right boundary of the left CTU. If the block located in the middle of the right boundary of the left CTU is not affine motion decoded, the upper left control point MV is considered unavailable.

[0160] In another example, the finite number of the upper left control point MV can be 1 or other integers. For the upper CTU, the upper left control point MV to be stored can be selected by selecting a 6-parameter affine motion model block in the bottom boundary of the upper CTU with the largest area. For the left CTU, the upper left control point MV to be stored can be selected by selecting a 6-parameter affine motion model block in the right boundary of the left CTU with the largest area.

[0161] In another example, the finite number of the upper left control point MV can be 1 or other integers. For the upper CTU, the upper left control point MV to be stored can be selected by selecting the 6-parameter affine motion model block in the bottom boundary of the upper CTU with the maximum width. For the left CTU, the upper left control point MV to be stored can be selected by selecting the 6-parameter affine motion model block in the right boundary of the left CTU with the maximum height.

[0162] In yet another example, the MVs of the left CTU are all stored and a limited number of upper left control point MVs are stored in an additional line buffer for the upper CTU. The selection of the stored upper left control point for the upper CTU may be similar to those described above.

[0163] An example of deriving an inherited affine motion vector predictor using line buffer reduction is described below. The variables (neiX, neiY) specify the coordinates of the top left sample point of the candidate block, the variables (neiW, neiH) specify the size of the candidate block, the variables (curX, curY) specify the coordinates of the top left sample point of the current block, and the variables (curW, curH) specify the size of the current block. The variable affTopLeftIsInLineBuf specifies whether the top left control point MV of the candidate block is stored in the line buffer.

[0164] If the candidate block is in the above CTU, the following rules apply:

[0165] (mvRB x ,mvRB y ) is set equal to the lower right control point MV of the candidate block, and (mvLB x ,mvLB y ) is set equal to the lower left control point MV of the candidate block.

[0166]

[0167]

[0168] Set the values ​​of posNeiX and posNeiY equal to the x and y coordinates of the top left sample point of the candidate block.

[0169] If affTopLeftIsInLineBuf is true, then (mvLT x , mvLT y ) is set equal to the upper left control point MV of the candidate block.

[0170]

[0171]

[0172] (mvAnchor x , mvAnchor y ) is set equal to (mvLT x , mvLT y ).

[0173] otherwise

[0174] dMvVerX=-dMvHorY

[0175] dMvVerY=dMvHorX

[0176] Set posNeiY equal to posNeiY+neiH

[0177] (mvAnchor x , mvAnchor y ) is set equal to (mvLB x ,mvLB y )

[0178] Otherwise, if the candidate block is in the left CTU, the following rules apply:

[0179] (mvRB x ,mvRB y ) is set equal to the lower right control point MV of the candidate block, and

[0180] (mvRT x , mvRT y ) is set equal to the upper right control point MV of the candidate block.

[0181]

[0182]

[0183] If affTopLeftIsInLineBuf is true, then (mvLT x , mvLT y ) is set equal to the upper left control point MV of the candidate block.

[0184]

[0185]

[0186] (mvAnchor x , mvAnchor y ) is set equal to (mvLT x , mvLT y ).

[0187] otherwise

[0188] dMvHorX=dMvVerY

[0189] dMvHorY=-dMvVerX

[0190] Set posNeiX equal to posNeiX+neiW

[0191] (mvAnchor x, mvAnchor y ) is set equal to (mvRT x , mvRT y )

[0192] Otherwise, if the candidate block is in the current CTU, the following rules apply:

[0193] (mvRT x , mvRT y ) is set equal to the upper right control point MV of the candidate block, and

[0194] (mvLT x , mvLT y ) is set equal to the upper left control point MV of the candidate block.

[0195] (mvAnchor x , mvAnchor y ) is set equal to (mvLT x , mvLT y ).

[0196]

[0197]

[0198] If the affine motion model of the candidate block is a 6-parameter affine motion model, then (mvLB x , mvLTB y ) is set equal to the lower left control point MV of the candidate block.

[0199]

[0200]

[0201] otherwise

[0202] dMvVerX=-dMvHorY

[0203] dMvVerY=dMvHorX

[0204] The predicted upper left control point MV (v0x, v0y) of the current block is derived as follows:

[0205] v0x=mvAnchor x +dMvHorX*(curX-neiX)+dMvVerX*(curY-neiY)

[0206] v0y=mvAnchor y+dMvHorY*(curX-neiX)+dMvVerY*(curY-neiY)

[0207] The predicted upper right control point MV(v1x, v1y) of the current block is derived as follows:

[0208] v1x=mvAnchor x +dMvHorX*(curX+curW-neiX)+dMvVerX*(curY-neiY)

[0209] v1y=mvAnchor y +dMvHorY*(curX+curW-neiX)+dMvVerY*(curY-neiY)

[0210] The predicted lower left control point MV(v2x, v2y) of the current block is derived as follows:

[0211] v2x=mvAnchor x +dMvHorX*(curX-neiX)+dMvVerX*(curY+curH-neiY)

[0212] v2y=mvAnchor y +dMvHorY*(curX-neiX)+dMvVerY*(curY+curH-neiY)

[0213] The division used in the above technique can be replaced by scaling and right shifting the result. For example, if the candidate block is in the current CTU, the following rules apply:

[0214] (mvAnchor x , mvAnchor y ) is set equal to (mvLT x <<maxShift,mvLT y <<maxShift).

[0215] dMvHorX=(mvRT x -mvLT x )<<(maxShift-log2(neiW))

[0216] dMvHorY=(mvRT y -mvLT y)<<(maxShift-log2(neiW)), where <<is a bitwise left shift. The variable maxShift is the log2 of the maximum block size. For example, setting maxShift equal to 7 indicates that the maximum block size is 128.

[0217] If the affine motion model of the candidate block is a 6-parameter affine motion model, then (mvLB x ,mvLB y ) is set equal to the lower left control point MV of the candidate block.

[0218] dMvVerX=(mvLB x -mvLT x )<<(maxShift-log2(neiH))

[0219] dMvVerY=(mvLB y -mvLT y )<<(maxShift-log2(neiH))

[0220] otherwise

[0221] dMvVerX=-dMvHorY

[0222] dMvVerY=dMvHorX

[0223] Set the offset to 1 << (maxShift-1)

[0224] The predicted upper left control point MV (v0x, v0y) of the current block is derived as follows:

[0225] v0x=mvAnchor x +dMvHorX*(curX-neiX)+dMvVerX*(curY-neiY)

[0226] v0y=mvAnchor y +dMvHorY*(curX-neiX)+dMvVerY*(curY-neiY)

[0227] v0x=v0x>0?(v0x+offset)

[0228] >>maxShift:-((-v0x+offset)>>maxShift)

[0229] v0y=v0y>0?(v0y+offset)

[0230] >>maxShift:-((-v0y+offset)>>maxShift)

[0231] The predicted upper right control point MV(v1x, v1y) of the current block is derived as follows:

[0232] v1x=mvAnchor x +dMvHorX*(curX+curW-neiX)+dMvVerX*(curY-neiY)

[0233] v1y=mvAnchor y +dMvHorY*(curX+curW-neiX)+dMvVerY*(curY-neiY)

[0234] v1x=v1x>0?(v1x+offset)

[0235] >>maxShift:-((-v1x+offset)>>maxShift)

[0236] v1y=v1y>0?(v1y+offset)

[0237] >>maxShift:-((-v1y+offset)>>maxShift)

[0238] The predicted lower left control point MV(v2x, v2y) of the current block is derived as follows:

[0239] v2x=mvAnchor x +dMvHorX*(curX-neiX)+dMvVerX*(curY+curH-neiY)

[0240] v2y=mvAnchor y +dMvHorY*(curX-neiX)+dMvVerY*(curY+curH-neiY)

[0241] v2x=v2x>0?(v2x+offset)

[0242] >>maxShift:-((-v2x+offset)>>maxShift)

[0243] v2y=v2y>0?(v2y+offset)

[0244] >>maxShift:-((-v2y+offset)>>maxShift)

[0245] Among them, >> is a bitwise right shift.

[0246] Techniques for using motion compensated motion vectors (eg, standard translational motion vectors) as control points in an inherited affine motion vector predictor are now described.

[0247] The video encoder 200 and the video decoder 300 can use sub-block based motion compensation to implement affine motion compensation. That is, the video encoder 200 and the video decoder 300 can derive a motion vector for each sub-block based on an affine motion model, and then apply standard block-based motion compensation or block matching according to the derived motion vector. The derivation of the sub-block motion vector is usually done by using the center coordinates of the sub-block.

[0248] In the case where the sub-block motion vector (e.g., for motion compensation) is stored in the motion buffer instead of the control point motion vector, the inherited affine motion vector predictor derivation process can be adjusted accordingly. More specifically, (neiX, neiY) and (neiW, neiH) can be modified according to the sub-block size. The size of the sub-block is (subBlkW, subBlkH). The value of (neiW, neiH) is modified to (neiW-subBlkW, neiH-subBlkH). In some examples, the modified value may not be a power of 2. The division used in the inherited affine motion vector predictor derivation process can be simplified by scaling according to a lookup table and shifting the result. The variables (neiX, neiY) can be modified so that the center of the sub-block where the control point is located is shifted. For example, if the candidate block is in the current CTU, the following rules apply.

[0249] The lookup table LUT is derived by LUT[x] = (x*(1<<LUTPREC)) / x, where LUTPREC is a predefined precision (e.g., 6 or other integer). The value of (neiX, neiY) is set equal to (neiX+subBlkW / 2, neiY+subBlkH / 2). (mvAnchor x , mvAnchor y ) is set equal to (mvLT x <<maxShift,mvLT y <<maxShift).

[0250] dMvHorX=(mvRT x -mvLT x )<<(maxShift-log2(neiW))

[0251] dMvHorY=(mvRT y -mvLT y)<<(maxShift-log2(neiW))

[0252] dMvHorX=dMvHorX*LUT[neiW-subBlkW]

[0253] dMvHorY=dMvHorY*LUT[neiW-subBlkW]

[0254] If the affine motion model of the candidate block is a 6-parameter affine motion model, then (mvLB x ,mvLB y ) is set equal to the lower left control point MV of the candidate block.

[0255] dMvVerX=(mvLB x -mvLT x )<<(maxShift-log2(neiH))

[0256] dMvVerY=(mvLB y -mvLT y )<<(maxShift-log2(neiH))

[0257] dMvVerX=dMvHorX*LUT[neiH-subBlkW]

[0258] dMvVerY=dMvHorY*LUT[neiW-subBlkW]

[0259] otherwise

[0260] dMvVerX=-dMvHorY

[0261] dMvVerY=dMvHorX

[0262] The offset is set equal to 1<<(maxShift-1)

[0263] The predicted upper left control point MV (v0x, v0y) of the current block is derived as:

[0264] v0x=mvAnchor x +(dMvHorX*(curX-neiX)>>LUTPREC)+(dMvVerX*(curY-neiY)>>LUTPREC)

[0265] v0y=mvAnchor y+(dMvHorY*(curX-neiX)>>LUTPREC)+(dMvVerY*(curY-neiY)>>LUTPREC)

[0266] v0x=v0x>0?(v0x+offset)

[0267] >>maxShift:-((-v0x+offset)>>maxShift)

[0268] v0y=v0y>0?(v0y+offset)

[0269] >>maxShift:-((-v0y+offset)>>maxShift)

[0270] The predicted upper right control point MV(v1x, v1y) of the current block is derived as:

[0271] v1x=mvAnchor x +(dMvHorX*(curX+curW-neiX)>>LUTPREC)+(dMvVerX*(curY-neiY)>>LUTPREC)

[0272] v1y=mvAnchor y +(dMvHorY*(curX+curW-neiX)>>LUTPREC)+(dMvVerY*(curY-neiY)>>LUTPREC)

[0273] v1x=v1x>0?(v1x+offset)

[0274] >>maxShift:-((-v1x+offset)>>maxShift)

[0275] v1y=v1y>0?(v1y+offset)

[0276] >>maxShift:-((-v1y+offset)>>maxShift)

[0277] The predicted lower left control point MV(v2x, v2y) of the current block is derived as:

[0278] v2x=mvAnchor x +(dMvHorX*(curX-neiX)>>LUTPREC)+(dMvVerX*(curY+curH-neiY)>>LUTPREC)

[0279] v2y=mvAnchor y +(dMvHorY*(curX-neiX)>>LUTPREC)+(dMvVerY*(curY+curH-neiY)>>LUTPREC)

[0280] v2x=v2x>0?(v2x+offset)

[0281] >>maxShift:-((-v2x+offset)>>maxShift)

[0282] v2y=v2y>0?(v2y+offset)

[0283] >>maxShift:-((-v2y+offset)>>maxShift)

[0284] Similar modifications may be applied to the case where the candidate block is in the upper CTU or the left CTU. If the candidate block is in the upper CTU and the value of affTopLeftIsInLineBuf for the candidate block is not true, (neiX, neiY) is set equal to (neiX+subBlkW / 2, neiY+neiH-subBlkH / 2). If the candidate block is in the left CTU and the value of affTopLeftIsInLineBuf for the candidate block is not true, (neiX, neiY) is set equal to (neiX+neiW-subBlkW / 2, neiY+subBlkH / 2).

[0285] The modified inherited affine motion vector predictor will now be described. The inherited affine motion vector predictor can be modified to create a new affine motion vector predictor. The modification can be done by replacing one (or both) control point motion vectors with the new motion vector.

[0286] In one example, the modified control point motion vector is at a fixed designated position (eg, an upper left control point, an upper right control point, or a lower left control point).

[0287] In another example, the modified control point motion vector depends on the position of the neighboring candidate block. For example, if the candidate block is at position A0 or A1 (e.g., see Figure 8 ), the modified control point MV is at the upper right control point. If the candidate block is at position B0 or ​​B1, the modified control point MV is at the lower left control point. If the candidate block is at position B2, the modified control point MV depends on the width and height of the candidate block. If the width is greater than the height, the modified control point MV is at the upper right control point, otherwise the modified control point MV is at the lower left control point.

[0288] In another example, the modified control point MV also depends on the target affine motion model for the current block. For example, if the target affine motion model for the current block is a 6-parameter affine motion model and the candidate block is at position B0 or ​​B1, the modified control point MV is at the lower left control point, otherwise the modified control point MV is at the upper right control point.

[0289] The affine motion vector predictor list construction for the affine advanced motion vector prediction (AMVP) mode will now be described.

[0290] Similar to the HEVC AMVP mode, when encoding a block using the affine AMVP mode, the video encoder 200 may signal an affine motion vector predictor index to the affine AMVP motion vector predictor list and a motion vector difference for each control point. The video decoder 300 constructs the same affine AMVP motion vector predictor list. The video decoder 300 receives the affine motion vector predictor index and retrieves the control point motion vector from the affine AMVP motion vector predictor list associated with the received index. The video decoder 300 adds the received motion vector difference to the control point motion vector retrieved from the affine AMVP motion vector predictor list to reconstruct the control point motion vector for the block of video data. The video decoder 300 then decodes the block of video data using the reconstructed control point motion vector using affine motion compensation.

[0291] The present disclosure describes techniques for constructing an affine AMVP motion vector predictor list. In particular, for some example blocks, the video encoder 200 and the video decoder 300 can construct an affine AMVP motion vector predictor list such that the list includes one or more inherited affine motion vector predictors, one or more constructed affine motion vector predictors, and one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector. By including multiple types of candidates in the affine AMVP motion vector predictor list, the video encoder 200 and the video decoder 300 can better ensure that more accurate candidates are available for control point motion vector prediction, thereby increasing bit rate and / or improving image quality.

[0292] In one example of the present disclosure, the video encoder 200 and the video decoder 300 may be configured to construct an affine AMVP motion vector predictor list using the following steps.

[0293] 1. The video encoder 200 and the video decoder 300 insert one or more inherited affine motion vector predictors derived from neighboring candidate blocks.

[0294] 2. If the number of existing predictors in the list is less than a predefined maximum number, the video encoder 200 and video decoder 300 insert one or more constructed affine motion vector predictors.

[0295] 3. If the number of existing predictors in the list is still less than a predefined maximum number after inserting both inherited and constructed affine motion vector predictors, the video encoder 200 and the video decoder 300 insert one or more affine motion vector predictors that make all control point motion vectors equal to a derived motion vector (e.g., also referred to as a specified motion vector).

[0296] As can be seen from the above techniques, for some blocks, when sufficient (e.g., up to a predefined maximum number) inherited affine motion vector predictors are available from neighboring blocks, the video encoder 200 and the video decoder 300 may only insert inherited affine motion vector predictors. For other example blocks, the video encoder 200 and the video decoder may only insert inherited affine motion vector predictors and constructed affine motion vector predictors. However, according to the techniques of the present disclosure, when neighboring blocks of the currently decoded block have less than a predefined maximum number of inherited and / or constructed affine motion vector predictors, the video encoder 200 and the video decoder 300 may further add one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector. In this way, a complete affine AMVP motion vector predictor list can be constructed regardless of the number of available inherited or constructed affine motion vector predictors.

[0297] Therefore, in one example of the present disclosure, the video encoder 200 may be configured to receive a video data block to be encoded using an affine advanced motion vector prediction (AMVP) mode. The video encoder 200 may also be configured to construct an affine AMVP motion vector predictor list of candidate control point motion vectors for the video data block, the affine AMVP motion vector predictor list including one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector. In this example, the affine AMVP motion vector predictor list may further include at least one or more inherited affine motion vector predictors or one or more constructed affine motion vector predictors. That is, in some examples, the affine AMVP motion vector predictor list may include an inherited affine motion vector predictor or a constructed affine motion vector predictor, together with an affine motion vector predictor that makes all control point motion vectors equal to a specified motion vector. This example may be obtained when the maximum number of candidates in the affine AMVP motion vector predictor list is 2. Of course, in other examples, the affine AMVP motion vector predictor list may be greater than 2. In those examples, there may be multiple inherited affine motion vector predictors, constructed affine motion vector predictors, and affine motion vector predictors that make all control point motion vectors equal to a specified motion vector.

[0298] Techniques for determining the specified motion vector will be described in more detail below.Video encoder 200 may be further configured to determine a control point motion vector for a block of video data from the affine AMVP motion vector predictor list and encode the block of video data using the determined control point motion vector.

[0299] In one example, as described above, in order to construct an affine AMVP motion vector predictor list of candidate control point motion vectors for a block of video data, the video encoder 200 is configured to insert one or more inherited affine motion vector predictors into the affine AMVP motion vector predictor list. The video encoder 200 may also be configured to insert one or more constructed affine motion vector predictors into the affine AMVP motion vector predictor list if the number of the one or more inherited affine motion vector predictors is less than a predefined maximum number of the affine AMVP motion vector predictor list. The video encoder 200 may further be configured to insert one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector into the affine AMVP motion vector predictor list if the number of the one or more inherited affine motion vector predictors and the one or more constructed affine motion vector predictors is less than a predefined maximum number of the affine AMVP motion vector predictor list.

[0300] The video encoder 200 may be further configured to determine candidate control point motion vectors in an affine AMVP motion vector predictor list, encode an index to the affine AMVP motion vector predictor list corresponding to the determined candidate control point motion vectors, determine a motion vector difference for each control point motion vector for the block relative to the determined candidate control point motion vector, and encode the motion vector difference.

[0301] In a reciprocal manner, the video decoder 300 can be configured to receive a block of video data encoded using an affine advanced motion vector prediction (AMVP) mode. The video decoder 300 can be further configured to construct an affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, the affine AMVP motion vector predictor list including one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector. Techniques for determining the specified motion vector will be described in more detail below. The video decoder 300 can be further configured to determine the control point motion vector for the block of video data from the affine AMVP motion vector predictor list, and decode the block of video data using the determined control point motion vector.

[0302] In one example, as described above, in order to construct an affine AMVP motion vector predictor list of candidate control point motion vectors for a block of video data, the video decoder 300 is configured to insert one or more inherited affine motion vector predictors into the affine AMVP motion vector predictor list. The video decoder 300 may be further configured to insert one or more constructed affine motion vector predictors into the affine AMVP motion vector predictor list if the number of the one or more inherited affine motion vector predictors is less than a predefined maximum number of the affine AMVP motion vector predictor list. The video decoder 300 may be further configured to insert one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector into the affine AMVP motion vector prediction list if the number of the one or more inherited affine motion vector predictors and the one or more constructed affine motion vector predictors is less than a predefined maximum number of the affine AMVP motion vector predictor list.

[0303] To determine the control point motion vector for the block, the video decoder 300 may be configured to receive an index to the affine AMVP motion vector predictor list, and receive a motion vector difference for each control point motion vector for the block. That is, the video decoder 300 may receive a motion vector difference for each of two (e.g., for a 4-parameter affine motion model) or three (e.g., for a 6-parameter affine motion model) control point motion vectors of a particular candidate indicated by the index to the affine AMVP motion vector predictor list. The video decoder 300 may be configured to retrieve the candidate control point motion vector associated with the index, and add the motion vector difference for each control point motion vector for the block to the candidate control point motion vector to determine the control point motion vector for the block.

[0304] The video encoder 200 and the video decoder 300 may be configured to insert the inherited affine motion vector predictor using one or more different insertion orders. Fig.11 The positions of potential inherited affine motion vector predictors relative to the current block are shown in . Possible positions include relative positions A0, A1, A2, B0, B1, B2, B3, C0, and C1. In the following description, a block is "available" if it meets the criteria for an associated type with an affine motion vector candidate. For example, if a candidate block is an affine decoded block for an inherited affine motion vector predictor, the candidate block is available. If the candidate block is decoded using a different mode, the candidate block is not available. Similarly, if a candidate block is an inter-frame prediction block for a constructed affine motion vector predictor, the candidate block is available. If the candidate block is decoded using a different mode, the candidate block is not available.

[0305] In one example, the video encoder 200 and the video decoder 300 may be configured to insert the inherited affine motion vector predictor into the affine AMVP motion vector predictor list in the following order:

[0306] - If the A1 candidate block is available and is coded using an affine motion model, insert the inherited affine motion vector predictor from A1 into the list and set availableA1 equal to true, otherwise set availableA1 equal to false.

[0307] - If availableA1 is false and the A0 candidate block is available and it is coded using an affine motion model, then the inherited affine motion vector predictor from A0 is inserted into the list.

[0308] - If the B1 candidate block is available and it is coded using an affine motion model, insert the inherited affine motion vector predictor from B1 into the list and set availableB1 equal to true, otherwise set availableB1 equal to false.

[0309] - If availableB1 is false and the B0 candidate block is available and it is coded using an affine motion model, insert the inherited affine motion vector predictor from B0 into the list and set availableB0 equal to true, otherwise set availableB0 equal to false.

[0310] - If availableB1 is false and availableB0 is false, and the B2 candidate block is available and it is coded using an affine motion model, then the inherited affine motion vector predictor from B2 is inserted into the list.

[0311] In another example, the following rules apply:

[0312] - If the A0 candidate block is available and it is coded using an affine motion model, insert the inherited affine motion vector predictor from A0 into the list and set availableA0 equal to true, otherwise set availableA0 equal to false.

[0313] - If availableA0 is false and the A1 candidate block is available and it is coded using an affine motion model, then insert the inherited affine motion vector predictor from A1 into the list.

[0314] - If the B0 candidate block is available and it is coded using an affine motion model, insert the inherited affine motion vector predictor from B0 into the list and set availableB0 equal to true, otherwise set availableB0 equal to false.

[0315] - If availableB0 is false and the B1 candidate block is available and it is coded using an affine motion model, insert the inherited affine motion vector predictor from B1 into the list and set availableB1 equal to true, otherwise set availableB1 equal to false.

[0316] - If availableB1 is false and availableB0 is false, and the B2 candidate block is available and it is coded using an affine motion model, then the inherited affine motion vector predictor from B2 is inserted into the list.

[0317] In yet another example, the following rules apply:

[0318] - If the A1 candidate block is available and it is coded using an affine motion model, insert the inherited affine motion vector predictor from A1 into the list and set availableA1 equal to true, otherwise set availableA1 equal to false.

[0319] - If availableA1 is false and the A0 candidate block is available and it is coded using an affine motion model, then the inherited affine motion vector predictor from A0 is inserted into the list.

[0320] - If the B1 candidate block is available and it is coded using an affine motion model, insert the inherited affine motion vector predictor from B1 into the list and set availableB1 equal to true, otherwise set availableB1 equal to false.

[0321] - If availableB1 is false and the B0 candidate block is available and it is coded using an affine motion model, insert the inherited affine motion vector predictor from B0 into the list and set availableB0 equal to true, otherwise set availableB0 equal to false.

[0322] - If the number of existing predictors in the list is less than a predefined maximum number and a B2 candidate block is available and it is coded using an affine motion model, then the inherited affine motion vector predictor from B2 is inserted into the list.

[0323] In yet another example, the following rules apply:

[0324] - If the A0 candidate block is available and it is coded using an affine motion model, insert the inherited affine motion vector predictor from A0 into the list and set availableA0 equal to true, otherwise set availableA0 equal to false.

[0325] - If availableA0 is false and the A1 candidate block is available and it is coded using an affine motion model, then the inherited affine motion vector predictor from A1 is inserted into the list.

[0326] - If the B0 candidate block is available and it is coded using an affine motion model, insert the inherited affine motion vector predictor from B0 into the list and set availableB0 equal to true, otherwise set availableB0 equal to false.

[0327] - If availableB0 is false and the B1 candidate block is available and it is coded using an affine motion model, insert the inherited affine motion vector predictor from B1 into the list and set availableB1 equal to true, otherwise set availableB1 equal to false.

[0328] - If the number of existing predictors in the list is less than a predefined maximum number and a B2 candidate block is available and it is coded using an affine motion model, then the inherited affine motion vector predictor from B2 is inserted into the list.

[0329] In yet another example, the following rules apply:

[0330] - If an A0 candidate block is available and it is coded using an affine motion model, the inherited affine motion vector predictor from A0 is inserted into the list.

[0331] - If the number of existing predictors in the list is less than a predefined maximum number and a B0 candidate block is available and it is coded using an affine motion model, then the inherited affine motion vector predictor from B0 is inserted into the list.

[0332] - If the number of existing predictors in the list is less than a predefined maximum number and a B1 candidate block is available and it is coded using an affine motion model, then the inherited affine motion vector predictor from B1 is inserted into the list.

[0333] - If the number of existing predictors in the list is less than a predefined maximum number and an A1 candidate block is available and it is coded using an affine motion model, then the inherited affine motion vector predictor from A1 is inserted into the list.

[0334] - If the number of existing predictors in the list is less than a predefined maximum number and a B2 candidate block is available and it is coded using an affine motion model, then the inherited affine motion vector predictor from B2 is inserted into the list.

[0335] In some examples, the video encoder 200 and the video decoder 300 may be configured to decode the blocks in a flexible decoder order. In the case of a flexible decoder order, such as Fig.11 As shown in , blocks located at C0 and C1 may be decoded before the current block and the blocks at A0 and A1. In this case, the inherited affine motion vector predictor from A0 and A1 described above may be replaced by the inherited affine motion vector predictor from C0 and C1.

[0336] The video encoder 200 and the video decoder 300 may be configured to insert one or more constructed affine motion vector predictors into the affine AMVP motion vector predictor list using one or more techniques described below.

[0337] For the 6-parameter affine motion model, the constructed affine motion vector predictor includes the upper left control point motion vector, the upper right control point motion vector and the lower left control point motion vector. For the 4-parameter affine motion model, the constructed affine motion vector predictor includes the upper left control point motion vector and the upper right control point motion vector.

[0338] In one example, the video encoder 200 and the video decoder 300 may add the constructed affine motion vector predictor to the affine AMVP motion vector predictor list as follows:

[0339] - The upper left control point MV is derived from the first available MV from the block in position {B2, B3, A2}.

[0340] - The upper right control point MV is derived from the first available MV from the block in position {B0, B1}.

[0341] - The lower left control point MV is derived from the first available MV from the block in position {A0, A1}.

[0342] In another example, the following rules apply:

[0343] - The upper left control point MV is derived from the first available MV from the block in position {B2, B3, A2}.

[0344] - The upper right control point MV is derived from the first available MV from the block in position {B1, B0}.

[0345] - The lower left control point MV is derived from the first available MV from the block in position {A1, A0}.

[0346] In yet another example, the following rules apply:

[0347] - The top left control point MV is derived from the first available MV from the block in position B2.

[0348] - The upper right control point MV is derived from the first available MV from the block in position {B1, B0}.

[0349] - The lower left control point MV is derived from the first available MV from the block in position {A1, A0}.

[0350] In yet another example, the following rules apply:

[0351] - The top left control point MV is derived from the first available MV from the block in position B2.

[0352] - The upper right control point MV is derived from the first available MV from the block in position {B0, B1}.

[0353] - The lower left control point MV is derived from the first available MV from the block in position {A0, A1}.

[0354] In some examples, if the lower left control point MV (v2x, v2y) is unavailable and the current affine motion model is a 6-parameter affine motion model, the video encoder 200 and the video decoder 300 may be configured to derive the lower left control point motion using the upper left control point motion vector (v0x, v0y) and the upper right control point motion vector (v1x, v1y) as follows:

[0355] v2x=v0x-(v1y-v0y)*curH / curW

[0356] v2y=v0y-(v1x-v0x)*curH / curW

[0357] In another example, if the current affine motion model is a 6-parameter affine motion model and any control point motion vector is unavailable, the video encoder 200 and the video decoder 300 may be configured to mark the constructed affine motion vector predictor as unavailable.

[0358] In some examples, if the upper right control point motion vector (v1x, v1y) is not available, the video encoder 200 and the video decoder 300 may be configured to derive the upper right control point motion vector using the upper left control point motion vector (v0x, v0y) and the lower left control point motion vector (v2x, v2y) as follows:

[0359] v1x=v0x-(v2y-v0y)*curW / curH

[0360] v1y=v0y-(v2x-v0x)*curW / curH

[0361] In another example, if the upper left control point motion vector or the upper right control point motion vector is unavailable, the video encoder 200 and the video decoder 300 may be configured to mark the affine motion vector predictor used for construction of the 6-parameter affine motion model as unavailable.

[0362] As described above, in some examples, the video encoder 200 and the video decoder 300 add an affine motion vector predictor that makes all control point motion vectors equal to a specified motion vector to the affine AMVP motion vector predictor list. That is, depending on the affine motion model used, these types of affine motion vector predictors have the same value for each of the candidate two or three control point motion vectors. The video encoder 200 and the video decoder 300 can be configured to dynamically determine the specified motion vector for each block from the specified motion vector candidate list.

[0363] In one example, the video encoder 200 and the video decoder 300 may be configured to select the designated motion vector from an AMVP candidate list (eg, a HEVC AMVP candidate list) for standard translational motion vector prediction.

[0364] In another example, the video encoder 200 and the video decoder 300 may be configured to select the designated motion vector from the following list in order:

[0365] 1. Motion vector of the lower left control point in the constructed affine motion vector predictor.

[0366] 2. The upper right control point motion vector in the constructed affine motion vector predictor.

[0367] 3. The motion vector of the upper left control point in the constructed affine motion vector predictor.

[0368] 4. Temporal motion vector predictor (eg, a temporal motion vector predictor for standard translational motion vector prediction (eg, HEVC AMVP candidate list)).

[0369] 5. Zero Motion Vector

[0370] In some examples, the video encoder 200 and the video decoder 300 can be configured to construct an affine AMVP motion vector predictor list without any pruning. That is, duplicate candidates are not removed from the list. In another example, the simplified pruning described above is applied, where only one control point motion vector is compared.

[0371] Fig.12is a flow chart illustrating example operations of a video encoder 200 according to the techniques described above. In one example, the video encoder 200 may be configured to receive a block of video data to be encoded using an affine advanced motion vector prediction (AMVP) mode (1200), and to construct an affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, the affine AMVP motion vector predictor list including one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector (1202). The video encoder 200 may also be configured to determine a control point motion vector for the block of video data from the affine AMVP motion vector predictor list (1204), and to encode the block of video data using the determined control point motion vector (1206).

[0372] Fig.13 is a flow chart illustrating an example operation of a video decoder 300 according to the techniques described above. In one example, the video decoder 300 may be configured to receive a block of video data encoded using an affine advanced motion vector prediction (AMVP) mode (1300), and to construct an affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, the affine AMVP motion vector predictor list including one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector (1302). The video decoder 300 may be further configured to determine a control point motion vector for the block of video data from the affine AMVP motion vector predictor list (1304), and to decode the block of video data using the determined control point motion vector (1306).

[0373] In another example, the video encoder 200 and the video decoder 300 may be configured to first check two adjacent blocks to determine whether the two adjacent blocks are in the same PU. If the two adjacent blocks are in the same PU, the block that is the latter in the check order of the two adjacent blocks is skipped. For example, if A1 is in the same PU as A0, A1 is skipped. Similarly, if B1 is in the same PU as B0, B1 is skipped; and if B2 is in the same PU as B0 or ​​A0, B2 is skipped. Thereafter, when inserting the inherited affine motion vector predictor into the predictor list, the video encoder 200 and the video decoder 300 may be configured to apply simplified pruning, as described above, in which only one control point MV is compared. Simplified pruning may be applied to the inherited affine motion vector predictor and / or other affine motion vector predictors.

[0374] In yet another example, simplified pruning is applied to inherited affine motion vector predictors, while no pruning is applied to other affine motion vector predictors.

[0375] Techniques for affine motion vector predictor list construction for affine merge mode will now be discussed. In affine merge mode, inherited affine merge candidates are obtained by deriving an affine motion vector predictor for each reference list, if applicable. Modified inherited affine merge candidates are obtained by modifying the selected control point motion vectors for each reference list, if applicable. Constructed affine merge candidates are obtained by deriving a constructed affine motion vector predictor for each reference list, if applicable.

[0376] If a neighboring candidate block is inter-prediction coded and coded using affine motion compensation, then it can be said that the neighboring candidate block is available for inherited affine merge candidate derivation.

[0377] In one example technique, the video encoder 200 and the video decoder 300 may be configured to construct an affine merge candidate list as follows:

[0378] 1. If available, add inherited affine merge candidates derived from neighboring candidate blocks in the order A0, B0, B1, A1, B2.

[0379] 2. Add the constructed merge affine candidates in the order of the following control point MV combinations, where MV0 is the control point MV at the upper left control point, MV1 is at the upper right control point, MV2 is at the lower left control point, and MV3 is at the lower right control point. MV0 is derived from the first available MV in {B2, B3, A2}, MV1 is derived from the first available in {B0, B1}, and MV2 is derived from the first available in {A0, A1}. MV3 is derived from the temporal merge candidate (e.g., as in HEVC).

[0380] a.{MV0, MV1, MV2}

[0381] b.{MV0, MV1, MV3}

[0382] c.{MV0, MV2, MV3}

[0383] d.{MV1, MV2, MV3}

[0384] e.{MV0,MV1}

[0385] f.{MV1, MV2}

[0386] g.{MV0,MV3}

[0387] h.{MV0,MV2}

[0388] i.{MV1,MV3}

[0389] j.{MV2, MV3}

[0390] 3. Add zero MV candidates, where each control point MV is a zero MV.

[0391] In another example, the video encoder 200 and the video decoder 300 may be configured to construct an affine merge candidate as follows:

[0392] 1. If available, add inherited affine merge candidates derived from neighboring candidate blocks in the order A0, B0, B1, A1, B2.

[0393] 2. Add the modified inherited affine merge candidates in the same order as the inherited affine merge candidates.

[0394] 3. Add the constructed affine merge candidates in the order of the following control point MV combinations, where MV0 is the control point MV at the upper left control point, MV1 is at the upper right control point, MV2 is at the lower left control point, and MV3 is at the lower right control point. MV0 is derived from the first available MV in {B2, B3, A2}, MV1 is derived from the first available in {B0, B1}, and MV2 is derived from the first available in {A0, A1}. MV3 is derived from the time domain merge candidate (e.g., as in HEVC).

[0395] a.{MV0, MV1, MV2}

[0396] b.{MV0, MV1, MV3}

[0397] c.{MV0, MV2, MV3}

[0398] d.{MV1, MV2, MV3}

[0399] e.{MV0,MV1}

[0400] f.{MV1, MV2}

[0401] g.{MV0,MV3}

[0402] h.{MV0,MV2}

[0403] i.{MV1,MV3}

[0404] j.{MV2, MV3}

[0405] 4. Add zero MV candidates, where each control point MV is a zero MV.

[0406] In yet another example, the video encoder 200 and the video decoder 300 may be configured to construct an affine merge candidate list as follows:

[0407] 1. If available, add inherited affine merge candidates derived from neighboring candidate blocks in the order A0, B0, B1, A1, B2.

[0408] 2. Add the constructed affine merge candidates in the order of the following control point MV combinations, where MV0 is the control point MV at the upper left control point, MV1 is at the upper right control point, MV2 is at the lower left control point, and MV3 is at the lower right control point. MV0 is derived from the first available MV in {B2, B3, A2}, MV1 is derived from the first available in {B0, B1}, and MV2 is derived from the first available in {A0, A1}. MV3 is derived from the temporal merge candidate (e.g., as in HEVC).

[0409] a.{MV0, MV1, MV2}

[0410] b.{MV0,MV1}

[0411] c.{MV1, MV2}

[0412] d.{MV0,MV2}

[0413] 3. Add zero MV candidates, where each control point MV is a zero MV.

[0414] In yet another example, the video encoder 200 and the video decoder 300 may be configured to construct an affine merge candidate list as follows:

[0415] 1. If available, add inherited affine merge candidates derived from neighboring candidate blocks in the order A0, B0, B1, A1, B2.

[0416] 2. Add the constructed affine merge candidates in the order of the following control point MV combinations, where MV0 is the control point MV at the upper left control point, MV1 is at the upper right control point, MV2 is at the lower left control point, and MV3 is at the lower right control point. MV0 is derived from the first available MV in {B2, B3, A2}, MV1 is derived from the first available in {B0, B1}, and MV2 is derived from the first available in {A0, A1}. MV3 is derived from the temporal merge candidate (e.g., as in HEVC).

[0417] a.{MV0, MV1, MV3}

[0418] b.{MV0, MV2, MV3}

[0419] c.{MV1, MV2, MV3}

[0420] d.{MV0, MV3}

[0421] e.{MV1,MV3}

[0422] f.{MV2, MV3}

[0423] 3. Add zero MV candidates, where each control point MV is a zero MV.

[0424] In yet another example, the video encoder 200 and the video decoder 300 may be configured to construct an affine merge candidate list as follows:

[0425] 1. If available, add inherited affine merge candidates derived from neighboring candidate blocks in the order A0, B0, B1, A1, B2.

[0426] 2. Add the modified inherited affine merge candidates in the same order as the inherited affine merge candidates.

[0427] 3. Add the constructed affine merge candidates in the order of the following control point MV combinations, where MV0 is the control point MV at the upper left control point, MV1 is at the upper right control point, MV2 is at the lower left control point, and MV3 is at the lower right control point. MV0 is derived from the first available MV in {B2, B3, A2}, MV1 is derived from the first available in {B0, B1}, and MV2 is derived from the first available in {A0, A1}. MV3 is derived from the time domain merge candidate (e.g., as in HEVC).

[0428] a.{MV0, MV1, MV3}

[0429] b.{MV0, MV2, MV3}

[0430] c.{MV1, MV2, MV3}

[0431] d.{MV0, MV3}

[0432] e.{MV1,MV3}

[0433] f.{MV2, MV3}

[0434] 4. Add zero MV candidates, where each control point MV is a zero MV.

[0435] Note that if three MVs are used and the combination is not {MV0, MV1, MV2}, the candidate is converted to a combination of {MV0, MV1, MV2}. For example, if the combination is {MV1, MV2, MV3}, an affine motion model is derived, and MV0 is derived given the affine motion model.

[0436] In yet another example, the video encoder 200 and the video decoder 300 may be configured to derive MV1 from the first available one of {B0, B1}, and derive MV2 from the first available one of {A0, A1}. However, MV0 may be selected from one of {B2, B3, A2} in sequence. Therefore, the maximum number of constructed affine merge candidates is three.

[0437] Other export techniques for exporting MV0

[0438] The video encoder 200 and the video decoder 300 may be configured to derive the control point motion vector MV0 from an inherited affine motion vector predictor. For example, the video encoder 200 and the video decoder 300 may be configured to derive MV0 from an inherited affine motion vector predictor (MVP) from blocks B2, B3, or A2.

[0439] In one example, the video encoder 200 and the video decoder 300 may be configured to derive only one MV0.

[0440] In some examples, the video encoder 200 and the video decoder 300 may be configured to sequentially check the inherited affine MVPs for blocks B2, B3, and A2 until the first available one is found. If an inherited affine MVP is found, the video encoder 200 and the video decoder 300 may be configured to use the upper left control point MV as MV0. Otherwise, the video encoder 200 and the video decoder 300 may be configured to sequentially check the standard translation MVPs for blocks B2, B3, and A2 until the first available one is found. If a standard translation MVP is found, the video encoder 200 and the video decoder 300 may be configured to use the standard translation MVP as MV0.

[0441] In another example, the video encoder 200 and the video decoder 300 may be configured to check the inherited affine MVP for block B2. If the inherited affine MVP is found, the video encoder 200 and the video decoder 300 may be configured to use the upper left control point MV as MV0. Otherwise, the video encoder 200 and the video decoder 300 may be configured to check the standard translation MVP for blocks B2, B3, and A2 in sequence until the first available one is found. If the standard translation MVP is found, the video encoder 200 and the video decoder 300 may be configured to use the standard translation MVP as MV0.

[0442] In another example, the video encoder 200 and the video decoder 300 may be configured to derive a plurality of control point motion vectors MV0.

[0443] In some examples, the video encoder 200 and the video decoder 300 may be configured to sequentially check the inherited affine MVP for blocks B2, B3, and A2. If the inherited affine MVP is found, the video encoder 200 and the video decoder 300 may be configured to use the upper left control point NV as the MV0 candidate. Then, the video encoder 200 and the video decoder 300 may be configured to sequentially check the standard translation MVP for blocks B2, B3, and A2. If the standard translation MVP is found, the video encoder 200 and the video decoder 300 may be configured to use the standard translation MVP as the MV0 candidate. The maximum number of MV0 candidates may be predefined, such as 2, 3, or other integers. The video encoder 200 and the video decoder 300 may be configured to apply a pruning process to remove duplication.

[0444] In some examples, the video encoder 200 and the video decoder 300 may be configured to check the inherited affine MVP for block B2. If the inherited affine MVP is found, the video encoder 200 and the video decoder 300 may be configured to use the upper left control point MV as the MV0 candidate. Then, the video encoder 200 and the video decoder 300 may be configured to check the standard translation MVP for blocks B2, B3, and A2 in sequence. If the standard translation MVP is found, the video encoder 200 and the video decoder 300 may be configured to use the standard translation MVP as the MV0 candidate. The maximum number of MV0 candidates may be predefined, such as 2, 3, or other integers. The video encoder 200 and the video decoder 300 may be configured to apply a pruning process to remove duplication.

[0445] The inspection order of B2, B3, and A2 can be switched.

[0446] Other derivation techniques for deriving MV1

[0447] In some examples, the video encoder 200 and the video decoder 300 may be configured to derive MV1 through an inherited affine motion vector predictor. For example, the video encoder 200 and the video decoder 300 may be configured to derive MV1 from an inherited affine MVP from block B0 or ​​B1.

[0448] In one approach, the video encoder 200 and the video decoder 300 may be configured to derive only one MV1.

[0449] In some examples, the video encoder 200 and the video decoder 300 may be configured to sequentially check the inherited affine MVPs for blocks B0 and B1 until the first available one is found. If the inherited affine MVP is found, the video encoder 200 and the video decoder 300 may be configured to use the upper left control point MV as MV1. Otherwise, the video encoder 200 and the video decoder 300 may be configured to sequentially check the standard translation MVPs for blocks B0 and B1 until the first available one is found. If the standard translation MVP is found, the video encoder 200 and the video decoder 300 may be configured to use the standard translation MVP as MV1.

[0450] In another example, multiple MV1s are derived.

[0451] In some examples, the video encoder 200 and the video decoder 300 may be configured to sequentially check the inherited affine MVP for blocks B0 and B1. If the inherited affine MVP is found, the video encoder 200 and the video decoder 300 may be configured to use the upper left control point MV as a candidate for MV1. Then, the video encoder 200 and the video decoder 300 may be configured to sequentially check the standard translation MVP for blocks B0 and B1. If the standard translation MVP is found, the video encoder 200 and the video decoder 300 may be configured to use the standard translation MVP as a candidate for MV1. The maximum number of candidates for MV1 may be predefined, such as 2, 3, or other integers. The video encoder 200 and the video decoder 300 may be configured to apply a pruning process to remove duplication.

[0452] The order of checking B0 and B1 can be switched.

[0453] Other derivation techniques for deriving MV2

[0454] In some examples, the video encoder 200 and the video decoder 300 may be configured to derive MV2 through an inherited affine motion vector predictor. For example, the video encoder 200 and the video decoder 300 may be configured to derive MV2 from an inherited affine MVP from block A0 or A1.

[0455] In one example, the video encoder 200 and the video decoder 300 may be configured to derive only one MV2.

[0456] In some examples, the video encoder 200 and the video decoder 300 may be configured to sequentially check the inherited affine MVPs for blocks A0 and A1 until the first available one is found. If the inherited affine MVP is found, the video encoder 200 and the video decoder 300 may be configured to use the upper left control point MV as MV2. Otherwise, the video encoder 200 and the video decoder 300 may be configured to sequentially check the standard translation MVPs for blocks A0 and A1 until the first available one is found. If the standard translation MVP is found, the video encoder 200 and the video decoder 300 may be configured to use the standard translation MVP as MV2.

[0457] In another example, the video encoder 200 and the video decoder 300 may be configured to derive a plurality of MV2s.

[0458] In some examples, the video encoder 200 and the video decoder 300 may be configured to sequentially check the inherited affine MVP for blocks A0 and A1. If the inherited affine MVP is found, the video encoder 200 and the video decoder 300 may be configured to use the upper left control point MV as a candidate for MV2. Then, the video encoder 200 and the video decoder 300 may be configured to sequentially check the standard translation MVP for blocks A0 and A1. If the standard translation MVP is found, the video encoder 200 and the video decoder 300 may be configured to use the standard translation MVP as a candidate for MV2. The maximum number of candidates for MV2 may be predefined, such as 2, 3, or other integers. The video encoder 200 and the video decoder 300 may be configured to apply a pruning process to remove duplication.

[0459] The order in which A0 and A1 are checked can be switched.

[0460] Other derivation techniques for deriving MV3

[0461] In the case of flexible decoder order, the video encoder 200 and the video decoder 300 may be configured to decode the block at position C0 or / and C1 before the current block. Then, similar to the above description, the video encoder 200 and the video decoder 300 may be configured to derive MV3 from the inherited affine MVP from C0 or / and C1, and / or from the standard translation MVP from C0 and / or C1. The video encoder 200 and the video decoder 300 may be configured to derive MVE through a temporal motion vector predictor (TMVP).

[0462] Affine MVP constructed using multiple MV0 candidates

[0463] In one example, the video encoder 200 and the video decoder 300 may be configured to use multiple MV0 candidates, but only use one MV1 and one MV2. Then, the video encoder 200 and the video decoder 300 may be configured to derive multiple constructed affine MVPs based on the multiple MV0 candidates, for example, the constructed affine MVPs are different for MV0.

[0464] Other insertion techniques for inherited affine motion vector predictors

[0465] The interpolation method described in this article can be applied to construct an affine merge candidate list.

[0466] Other interpolation techniques for constructing affine motion vector predictors

[0467] Other insertion orders of the constructed affine MVP can be applied.

[0468] In some examples, the following rules apply.

[0469] a. Check {MV0, MV1, MV2}. If multiple MV0 candidates are available, check multiple {MV0, MV1, MV2} using the multiple MV0 candidates.

[0470] b. Check {MV0, MV1, MV3}

[0471] c. Check {MV0, MV2, MV3}

[0472] d. Check {MV1, MV2, MV3}

[0473] e. Check {MV0, MV1}

[0474] f. Check {MV0, MV2}

[0475] In another example, the following rules apply.

[0476] a. Check {MV0, MV1, MV2}. If multiple MV0 candidates are available, check multiple {MV0, MV1, MV2} using the multiple MV0 candidates.

[0477] b. Check {MV0, MV1, MV3}

[0478] c. Check {MV0, MV2, MV3}

[0479] d. Check {MV1, MV2, MV3}

[0480] e. Check {MV0, MV1}. If multiple MV0 candidates are available, check multiple {MV0, MV1} using the multiple MV0 candidates.

[0481] In yet another example, the following rules apply.

[0482] a. Check {MV0, MV1, MV2}. If multiple MV0 candidates are available, check multiple {MV0, MV1, MV2} using the multiple MV0 candidates.

[0483] b. If MV2 is not available, check {MV0, MV1}. If multiple MV0 candidates are available, check multiple {MV0, MV1} using the multiple MV0 candidates.

[0484] c. Check {MV0, MV1, MV3}

[0485] d. Check {MV0, MV2, MV3}

[0486] e. Check {MV1, MV2, MV3}

[0487] In yet another example, the following rules apply.

[0488] a. Check {MV0, MV1, MV2}. If multiple MV0 candidates are available, check multiple {MV0, MV1, MV2} using the multiple MV0 candidates.

[0489] b. Check {MV0, MV1}, and if multiple MV0 candidates are available, check multiple {MV0, MV1} using the multiple MV0 candidates.

[0490] Note that in case of flexible decoding order and C0 / C1 is decoded before A0 / A1, MV0 and MV3 described above are switched.

[0491] Insert ATMVP candidates into the affine merge candidate list

[0492] When a separate merge candidate list for sub-PU based merge mode is used, the sub-PU based advanced temporal motion vector prediction (ATMVP) candidate is inserted after the inherited affine merge candidate from A1. In another example, the ATMVP candidate is inserted in the first position of the merge candidate list, for example, before the affine merge candidate.

[0493] In another example of the present disclosure, an improved constructed affine motion predictor is described. In some examples, for a conventionally constructed affine motion predictor, the motion vector at the upper left control point can be predicted by the motion vector at B2, B3, or A3. The motion vector at the upper right control point can be predicted by the motion vector at B0 or ​​B1 And the motion vector at the lower left control point can be predicted by the motion vector at A0 or A1 According to the techniques of this disclosure, the improved constructed affine candidate is first predicted by the inherited affine motion predictor from its immediate neighboring blocks (if available).

[0494] If A3 is affine decoded, then the affine motion model of A3 is derived That is, the inherited affine motion predictor from A3 Otherwise, derive as described for the conventionally constructed affine motion predictor

[0495] If B0 / B1 is affine decoded, then the affine motion model of B0 / B1 is used to derive That is, the inherited affine motion predictor from B0 / B1 Otherwise, derive as described for the conventionally constructed affine motion predictor

[0496] If A0 / A1 is affine decoded, then the affine motion model of A0 / A1 is derived That is, the inherited affine motion predictor from A0 / A1 Otherwise, derive as described for the conventionally constructed affine motion predictor

[0497] In this way, if the inherited affine motion predictor from A0, A1, B0, B1, B2, B3, A3 has been derived, the corresponding control point MV of the constructed affine motion predictor can be derived together with the inherited affine motion predictor. In this way, the computational complexity can be reduced.

[0498] Adaptive affine motion vector difference prediction

[0499] The video encoder 200 and the video decoder 300 may be configured to predict the motion vector difference (MVD) of the upper right control point and the lower left control point by the MVD of the upper left control point. The video encoder 200 and the video decoder 300 may be configured to adaptively apply MVD prediction. If the affine MVP is an inherited affine MVP or the 3 control point MVs of the MVP are predicted by the same translation MV, the video encoder 200 and the video decoder 300 may be configured to apply MVD prediction. Otherwise, for example, if the affine MVP is a constructed affine MVP, the video encoder 200 and the video decoder 300 may be configured not to apply MVD prediction.

[0500] History-based affine motion vector prediction

[0501] As in history-based motion vector prediction, the video encoder 200 and the video decoder 300 may be configured to derive an inherited affine MVP from an affine MVP list maintained at the slice level. The video encoder 200 and the video decoder 300 may be configured to update the slice-level affine MVP list when a block is decoded by affine motion prediction. The video encoder 200 and the video decoder 300 may be configured to insert affine motion parameters for a block into the affine MVP list. When the number of candidates in the list reaches a predefined maximum value, the MVP is popped out (e.g., removed) according to a first-in, first-out rule. When the affine MVP is obtained from the list, the order of checking is opposite to the order of insertion. A history-based affine MVP, such as an affine MVP from a slice-level list, may be inserted after the constructed affine MVP. Note that when the affine motion parameters are inserted into the list, the position and width and height of the current block are also stored.

[0502] Affine motion vector predictor refinement using motion vector differences

[0503] The video encoder 200 and the video decoder 300 may be configured to refine the affine MVP by a motion vector difference (MVD). The video encoder 200 and the video decoder 300 may be configured to construct an affine MVP candidate list as in the above-mentioned affine merge mode, except that zero MV candidates are not included. Then, the video encoder 200 and the video decoder 300 may be configured to refine the designated control point MV of the affine MVP selected by the merge index by MVD.

[0504] In some examples, the designated control point MV is the upper left control point MV. In another example, the designated control point MV is the upper right control point MV. In yet another example, the designated control point MV is the lower left control point MV.

[0505] In yet another example, the designated control point MV depends on the selected affine MVP. For example, if the selected affine MVP is an inherited affine MVP from A0 / A1, the designated control point MV for refinement is the upper right control point MV; if the selected affine MVP is an inherited affine MVP from B0 / B1, the designated control point MV for refinement is the lower left control point MV; if the selected affine MVP is an inherited affine MVP from B2 / B3 / A2, the designated control point MV for refinement is (width>height?upper right control point MV:lower left control point MV); for another affine MVP, for example, a constructed affine MVP or an affine MVP from a slice-level list, the designated control point MV for refinement is predefined as the upper left control point MV.

[0506] If the affine MVP is bidirectional, the video encoder 200 and the video decoder 300 may be configured to mirror the MVDs in both directions so that only one MVD is signaled, and this one is derived by scaling the signaled MVD.

[0507] In some examples, the coding of the MVD may be the same as standard MVD coding.

[0508] In another example, the decoding of the motion vector difference can be the same as in U.S. Provisional Patent Application No. 62 / 697,860 or JVET-K0115 "CE4 Ultimate motion vector expression in JVET-J0024". Among them, MVD is expressed as prediction direction information, starting point, motion magnitude and motion direction. The starting point is the selected affine MVP, and the affine MVP list construction depends on the prediction direction information, that is, forward prediction, backward prediction or bidirectional prediction.

[0509] Fig.14 2 is a flowchart illustrating an example method for encoding a current block. The current block may include a current CU. Although the video encoder 200 ( Figure 1 and Figure 3 ), but it should be understood that other devices may be configured to perform similar Fig.14 method.

[0510] In this example, the video encoder 200 initially predicts the current block (350). For example, the video encoder 200 may form a prediction block for the current block. The video encoder 200 may then calculate a residual block for the current block (352). To calculate the residual block, the video encoder 200 may calculate the difference between the original uncoded block and the prediction block for the current block. The video encoder 200 may then transform and quantize the coefficients of the residual block (354). Next, the video encoder 200 may scan the quantized transform coefficients of the residual block (356). During or after the scan, the video encoder 200 may entropy encode the coefficients (358). For example, the video encoder 200 may encode the coefficients using CAVLC or CABAC. The video encoder 200 may then output entropy coded data for the coefficients of the block (360).

[0511] Fig.15 1 is a flowchart illustrating an example method for decoding a current video data block. The current block may include a current CU. Although the video decoder 300 ( Figure 1 and Figure 4 ), but it should be understood that other devices may be configured to perform similar Fig.15 method.

[0512] The video decoder 300 may receive entropy coded data for a current block, such as entropy coded prediction information and entropy coded data of coefficients of a residual block corresponding to the current block (370). The video decoder 300 may decode the entropy coded data to determine prediction information for the current block and reproduce coefficients of the residual block (372). The video decoder 300 may predict the current block (374), for example, using an intra-frame or inter-frame prediction mode indicated by the prediction information for the current block to calculate a prediction block for the current block. The video decoder 300 may then inverse scan the reproduced coefficients (376) to create a block of quantized transform coefficients. The video decoder 300 may then inverse quantize and inverse transform the coefficients to produce a residual block (378). The video decoder 300 may ultimately decode the current block (380) by combining the prediction block and the residual block.

[0513] It should be appreciated that, according to examples, certain actions or events of any technology described herein may be performed in a different sequence, may be added, merged, or omitted together (e.g., not all described actions or events are necessary for the practice of the technology). In addition, in some examples, actions or events may be processed concurrently rather than sequentially, such as by multithreading, interrupt processing, or multiple processors.

[0514] In one or more examples, the described functions may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted through a computer-readable medium as one or more instructions or codes and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media, which corresponds to tangible media such as data storage media, or communication media, including, for example, any media that facilitates the transfer of a computer program from one place to another according to a communication protocol. In this manner, computer-readable media may generally correspond to (1) a non-temporary tangible computer-readable storage medium, or (2) a communication medium such as a signal or carrier wave. Data storage media may be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, codes, and / or data structures to implement the techniques described in the present disclosure. A computer program product may include a computer-readable medium.

[0515] As an example and not limitation, such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage devices, flash memory or any other medium that can be used to store the required program code in the form of instructions or data structures and can be accessed by a computer. Moreover, any connection is appropriately referred to as a computer-readable medium. For example, if instructions are sent from a website, server or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) or wireless technology (such as infrared, radio and microwave), the definition of the medium includes coaxial cable, fiber optic cable, twisted pair, DSL or wireless technology such as infrared, radio and microwave. However, it should be understood that computer-readable storage media and data storage media do not include connections, carriers, signals or other temporary media, but are directed to non-temporary tangible storage media. Disks and optical disks as used in this application include compact discs (CDs), laser optical discs, optical optical discs, digital versatile discs (DVDs), floppy disks and blue-ray discs, wherein disks typically reproduce data magnetically, while optical discs reproduce data optically with lasers. The above combination should also be included in the scope of computer-readable media.

[0516] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Therefore, the term "processor" as used in this application may refer to any of the aforementioned structures or any other structure suitable for implementing the technology described in this application. In addition, in some aspects, the functions described in this application may be provided within dedicated hardware and / or software modules configured for encoding and decoding, or incorporated in a combined codec. Similarly, the technology may be fully implemented in one or more circuits or logic elements.

[0517] The techniques of the present disclosure may be implemented in a variety of devices or apparatuses including a wireless handset, an integrated circuit (IC), or a set of ICs (e.g., a chipset). Various components, modules, or units are described in the present disclosure to emphasize functional aspects of devices configured to perform the disclosed techniques, but do not necessarily need to be implemented by different hardware units. Rather, as described above, the various units may be combined in a codec hardware unit, or provided by a collection of interoperable hardware units, including one or more processors as described above in combination with appropriate software and / or firmware.

[0518] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

1. A method for decoding video data, the method comprising: Receiving a video data block encoded using an affine advanced motion vector prediction (AMVP) mode; constructing an affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, wherein the affine AMVP motion vector predictor list includes at least one or more inherited affine motion vector predictors or one or more constructed affine motion vector predictors, and wherein the affine AMVP motion vector predictor list also includes one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector; The designated motion vector is determined from a designated motion vector candidate list in the following order, wherein the designated motion vector candidate list is different from the affine AMVP motion vector predictor list: 1) a lower left control point motion vector in a constructed affine motion vector predictor, wherein the constructed affine motion vector predictor is a translation motion vector for predicting a specific control point motion vector of the affine AMVP mode, 2) The upper right control point motion vector in the constructed affine motion vector predictor, 3) The upper left control point motion vector in the constructed affine motion vector predictor, 4) Temporal motion vector predictor, and 5) Zero motion vector; determining a control point motion vector for the block of video data from the affine AMVP motion vector predictor list; and The block of video data is decoded using the determined control point motion vectors.

2. The method according to claim 1, wherein: Constructing the affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data comprises: inserting the one or more inherited affine motion vector predictors into the affine AMVP motion vector predictor list, if applicable; If the number of the one or more inherited affine motion vector predictors is less than a predefined maximum number of the affine AMVP motion vector predictor list, inserting the one or more constructed affine motion vector predictors into the affine AMVP motion vector predictor list, if available; and If the number of the one or more inherited affine motion vector predictors and the one or more constructed affine motion vector predictors is less than the predefined maximum number of the affine AMVP motion vector predictor list, the one or more affine motion vector predictors that make all control point motion vectors equal to the specified motion vector are inserted into the affine AMVP motion vector predictor list.

3. The method according to claim 1, wherein: Constructing the affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data comprises: The affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data is constructed without performing a pruning process.

4. The method according to claim 1, further comprising: The one or more inherited affine motion vector predictors are derived from control point motion vectors of neighboring blocks that are encoded using affine motion prediction.

5. The method according to claim 1, further comprising: The one or more constructed affine motion vector predictors are derived from motion vectors of neighboring blocks coded using inter-prediction.

6. The method according to claim 1, wherein: The video data block is decoded using a 6-parameter affine motion model, the method further comprising: The one or more constructed affine motion vector predictors are derived from motion vectors of neighboring blocks coded using inter prediction only if all control point motion vectors of the 6-parameter affine motion model are available.

7. The method according to claim 1, wherein: Determining the control point motion vector for the block comprises: Receiving an index into the affine AMVP motion vector predictor list; receiving a motion vector difference for each of said control point motion vectors of said block; retrieving the candidate control point motion vector associated with the index; and The motion vector differences for each of the control point motion vectors for the block are added to the candidate control point motion vectors to determine the control point motion vector for the block.

8. The method according to claim 1, further comprising: A picture is output for display, the picture comprising the decoded video data block.

9. A device configured to decode video data, the device comprising: A memory configured to store video data blocks encoded using an affine advanced motion vector prediction (AMVP) mode; as well as One or more processors in communication with the memory, the one or more processors being configured to: receiving the video data block; constructing an affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, wherein the affine AMVP motion vector predictor list includes at least one or more inherited affine motion vector predictors or one or more constructed affine motion vector predictors, and wherein the affine AMVP motion vector predictor list also includes one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector; The designated motion vector is determined from a designated motion vector candidate list in the following order, wherein the designated motion vector candidate list is different from the affine AMVP motion vector predictor list: 1) a lower left control point motion vector in a constructed affine motion vector predictor, wherein the constructed affine motion vector predictor is a translation motion vector for predicting a specific control point motion vector of the affine AMVP mode, 2) The upper right control point motion vector in the constructed affine motion vector predictor, 3) The upper left control point motion vector in the constructed affine motion vector predictor, 4) Temporal motion vector predictor, and 5) Zero motion vector; determining a control point motion vector for the block of video data from the affine AMVP motion vector predictor list; and The block of video data is decoded using the determined control point motion vectors.

10. The device according to claim 9, wherein: To construct the affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, the one or more processors are configured to: inserting the one or more inherited affine motion vector predictors into the affine AMVP motion vector predictor list, if applicable; if the number of the one or more inherited affine motion vector predictors is less than a predefined maximum number of the affine AMVP motion vector predictor list, inserting the one or more constructed affine motion vector predictors into the affine AMVP motion vector predictor list, if available; as well as If the number of the one or more inherited affine motion vector predictors and the one or more constructed affine motion vector predictors is less than the predefined maximum number of the affine AMVP motion vector predictor list, the one or more affine motion vector predictors that make all control point motion vectors equal to the specified motion vector are inserted into the affine AMVP motion vector predictor list.

11. The device according to claim 9, wherein: To construct the affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, the one or more processors are configured to: The affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data is constructed without performing a pruning process.

12. The device according to claim 9, wherein: The one or more processors are further configured to: The one or more inherited affine motion vector predictors are derived from control point motion vectors of neighboring blocks that are encoded using affine motion prediction.

13. The device according to claim 9, wherein: The one or more processors are further configured to: The one or more constructed affine motion vector predictors are derived from motion vectors of neighboring blocks coded using inter-prediction.

14. The device according to claim 9, wherein: The video data block is decoded using a 6-parameter affine motion model, and wherein the one or more processors are further configured to: The one or more constructed affine motion vector predictors are derived from motion vectors of neighboring blocks coded using inter prediction only if all control point motion vectors of the 6-parameter affine motion model are available.

15. The device according to claim 9, wherein: To determine the control point motion vector for the block, the one or more processors are configured to: Receiving an index into the affine AMVP motion vector predictor list; receiving a motion vector difference for each of said control point motion vectors of said block; retrieving the candidate control point motion vector associated with the index; as well as The motion vector difference of each of the control point motion vectors for the block is added to the candidate control point motion vectors to determine the control point motion vector for the block.

16. The apparatus according to claim 9, further comprising: A display is configured to display a picture, wherein the picture includes a decoded video data block.

17. A device configured to decode video data, the device comprising: Means for receiving a block of video data encoded using an affine advanced motion vector prediction (AMVP) mode; means for constructing an affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, wherein the affine AMVP motion vector predictor list includes at least one or more inherited affine motion vector predictors or one or more constructed affine motion vector predictors, and wherein the affine AMVP motion vector predictor list further includes one or more affine motion vector predictors that cause all control point motion vectors to be equal to a specified motion vector; Means for determining the designated motion vector from a designated motion vector candidate list in the following order, wherein the designated motion vector candidate list is different from the affine AMVP motion vector predictor list: 1) a lower left control point motion vector in a constructed affine motion vector predictor, wherein the constructed affine motion vector predictor is a translation motion vector for predicting a specific control point motion vector of the affine AMVP mode, 2) The upper right control point motion vector in the constructed affine motion vector predictor, 3) The upper left control point motion vector in the constructed affine motion vector predictor, 4) Temporal motion vector predictor, and 5) Zero motion vector; means for determining a control point motion vector for said block of video data from said affine AMVP motion vector predictor list; and Means for decoding the block of video data using the determined control point motion vector.

18. The device according to claim 17, wherein: The means for constructing the affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data comprises: means for inserting said one or more inherited affine motion vector predictors into said affine AMVP motion vector predictor list, if applicable; means for inserting the one or more constructed affine motion vector predictors into the affine AMVP motion vector predictor list, if available, if the number of the one or more inherited affine motion vector predictors is less than a predefined maximum number of the affine AMVP motion vector predictor list; A component for inserting the one or more affine motion vector predictors that make all control point motion vectors equal to the specified motion vector into the affine AMVP motion vector predictor list if the number of the one or more inherited affine motion vector predictors and the one or more constructed affine motion vector predictors is less than the predefined maximum number of the affine AMVP motion vector predictor list.

19. The device according to claim 17, wherein: The means for constructing an affine AMVP motion vector predictor list of the candidate control point motion vectors for the block of video data comprises: Means for constructing an affine AMVP motion vector predictor list of the candidate control point motion vectors for the block of video data without performing a pruning process.

20. A non-transitory computer-readable storage medium storing instructions that, when executed, cause one or more processors to: Receiving a video data block encoded using an affine advanced motion vector prediction (AMVP) mode; Constructing an affine AMVP motion vector predictor list of candidate control point motion vectors for the video data block, wherein: The affine AMVP motion vector predictor list includes at least one or more inherited affine motion vector predictors or one or more constructed affine motion vector predictors, and wherein the affine AMVP motion vector predictor list further includes one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector; The designated motion vector is determined from a designated motion vector candidate list in the following order, wherein the designated motion vector candidate list is different from the affine AMVP motion vector predictor list: 1) a lower left control point motion vector in a constructed affine motion vector predictor, wherein the constructed affine motion vector predictor is a translation motion vector for predicting a specific control point motion vector of the affine AMVP mode, 2) The upper right control point motion vector in the constructed affine motion vector predictor, 3) The upper left control point motion vector in the constructed affine motion vector predictor, 4) Temporal motion vector predictor, and 5) Zero motion vector; determining a control point motion vector for the block of video data from the affine AMVP motion vector predictor list; as well as The block of video data is decoded using the determined control point motion vectors.

21. The non-transitory computer-readable storage medium of claim 20, wherein: To construct the affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, the instructions cause the one or more processors to: inserting the one or more inherited affine motion vector predictors into the affine AMVP motion vector predictor list, if applicable; if the number of the one or more inherited affine motion vector predictors is less than a predefined maximum number of the affine AMVP motion vector predictor list, inserting the one or more constructed affine motion vector predictors into the affine AMVP motion vector predictor list, if available; as well as If the number of the one or more inherited affine motion vector predictors and the one or more constructed affine motion vector predictors is less than the predefined maximum number of the affine AMVP motion vector predictor list, the one or more affine motion vector predictors that make all control point motion vectors equal to the specified motion vector are inserted into the affine AMVP motion vector predictor list.

22. The non-transitory computer-readable storage medium of claim 20, wherein: To construct an affine AMVP motion vector predictor list of the candidate control point motion vectors for the block of video data, the instructions cause the one or more processors to: An affine AMVP motion vector predictor list of the candidate control point motion vectors for the block of video data is constructed without performing a pruning process.

23. A method for encoding video data, the method comprising: Receiving a block of video data to be encoded using an affine advanced motion vector prediction (AMVP) mode; constructing an affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, wherein the affine AMVP motion vector predictor list includes at least one or more inherited affine motion vector predictors or one or more constructed affine motion vector predictors, and wherein the affine AMVP motion vector predictor list also includes one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector; The designated motion vector is determined from a designated motion vector candidate list in the following order, wherein the designated motion vector candidate list is different from the affine AMVP motion vector predictor list: 1) a lower left control point motion vector in a constructed affine motion vector predictor, wherein the constructed affine motion vector predictor is a translation motion vector for predicting a specific control point motion vector of the affine AMVP mode, 2) The upper right control point motion vector in the constructed affine motion vector predictor, 3) The upper left control point motion vector in the constructed affine motion vector predictor, 4) Temporal motion vector predictor, and 5) Zero motion vector; determining a control point motion vector for the block of video data from the affine AMVP motion vector predictor list; and The block of video data is encoded using the determined control point motion vectors.

24. The method according to claim 23, wherein: Constructing the affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data comprises: inserting the one or more inherited affine motion vector predictors into the affine AMVP motion vector predictor list, if applicable; If the number of the one or more inherited affine motion vector predictors is less than a predefined maximum number of the affine AMVP motion vector predictor list, inserting the one or more constructed affine motion vector predictors into the affine AMVP motion vector predictor list, if available; and If the number of the one or more inherited affine motion vector predictors and the one or more constructed affine motion vector predictors is less than the predefined maximum number of the affine AMVP motion vector predictor list, the one or more affine motion vector predictors that make all control point motion vectors equal to the specified motion vector are inserted into the affine AMVP motion vector predictor list.

25. The method according to claim 23, wherein: Constructing an affine AMVP motion vector predictor list of the candidate control point motion vectors for the block of video data comprises: An affine AMVP motion vector predictor list of the candidate control point motion vectors for the block of video data is constructed without performing a pruning process.

26. The method of claim 23, further comprising: The one or more inherited affine motion vector predictors are derived from control point motion vectors of neighboring blocks coded using affine motion prediction.

27. The method of claim 23, further comprising: The one or more constructed affine motion vector predictors are derived from motion vectors of neighboring blocks coded using inter-prediction.

28. The method of claim 23, wherein: The video data block is encoded using a 6-parameter affine motion model, and the method further comprises: The one or more constructed affine motion vector predictors are derived from motion vectors of neighboring blocks coded using inter prediction only if all control point motion vectors of the 6-parameter affine motion model are available.

29. The method of claim 23, further comprising: Determining candidate control point motion vectors in the affine AMVP motion vector predictor; encoding an index to the affine AMVP motion vector predictor list corresponding to the determined candidate control point motion vector; determining a motion vector difference of each of the control point motion vectors for the block relative to the determined candidate control point motion vectors; as well as The motion vector difference is encoded.

30. The method of claim 23, further comprising: A picture including the block of video data is captured.

31. An apparatus configured to encode video data, the apparatus comprising: A memory configured to store video data blocks to be encoded using an affine advanced motion vector prediction (AMVP) mode; as well as One or more processors in communication with the memory, the one or more processors being configured to: receiving the video data block; constructing an affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, wherein the affine AMVP motion vector predictor list includes at least one or more inherited affine motion vector predictors or one or more constructed affine motion vector predictors, and wherein the affine AMVP motion vector predictor list also includes one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector; The designated motion vector is determined from a designated motion vector candidate list in the following order, wherein the designated motion vector candidate list is different from the affine AMVP motion vector predictor list: 1) a lower left control point motion vector in a constructed affine motion vector predictor, wherein the constructed affine motion vector predictor is a translation motion vector for predicting a specific control point motion vector of the affine AMVP mode, 2) The upper right control point motion vector in the constructed affine motion vector predictor, 3) The upper left control point motion vector in the constructed affine motion vector predictor, 4) Temporal motion vector predictor, and 5) Zero motion vector; determining a control point motion vector for the block of video data from the affine AMVP motion vector predictor list; and The block of video data is encoded using the determined control point motion vectors.

32. The device according to claim 31, wherein To construct the affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, the one or more processors are configured to: inserting the one or more inherited affine motion vector predictors into the affine AMVP motion vector predictor list, if applicable; if the number of the one or more inherited affine motion vector predictors is less than a predefined maximum number of the affine AMVP motion vector predictor list, inserting the one or more constructed affine motion vector predictors into the affine AMVP motion vector predictor list, if available; as well as If the number of the one or more inherited affine motion vector predictors and the one or more constructed affine motion vector predictors is less than the predefined maximum number of the affine AMVP motion vector predictor list, the one or more affine motion vector predictors that make all control point motion vectors equal to the specified motion vector are inserted into the affine AMVP motion vector predictor list.

33. The device according to claim 31, wherein To construct an affine AMVP motion vector predictor list of the candidate control point motion vectors for the block of video data, the one or more processors are configured to: An affine AMVP motion vector predictor list of the candidate control point motion vectors for the block of video data is constructed without performing a pruning process.

34. The device according to claim 31, wherein The one or more processors are further configured to: The one or more inherited affine motion vector predictors are derived from control point motion vectors of neighboring blocks coded using affine motion prediction.

35. The device according to claim 31, wherein The one or more processors are further configured to: The one or more constructed affine motion vector predictors are derived from motion vectors of neighboring blocks coded using inter-prediction.

36. The device according to claim 31, wherein The video data block is encoded using a 6-parameter affine motion model, and wherein the one or more processors are further configured to: The one or more constructed affine motion vector predictors are derived from motion vectors of neighboring blocks coded using inter prediction only if all control point motion vectors of the 6-parameter affine motion model are available.

37. The device according to claim 31, wherein The one or more processors are further configured to: Determining candidate control point motion vectors in the affine AMVP motion vector predictor; encoding an index to the affine AMVP motion vector predictor list corresponding to the determined candidate control point motion vector; determining a motion vector difference of each of the control point motion vectors for the block relative to the determined candidate control point motion vectors; as well as The motion vector difference is encoded.

38. The apparatus of claim 31 , further comprising: A camera is configured to capture a picture including the video data block.

39. An apparatus configured to encode video data, the apparatus comprising: Means for receiving a block of video data to be encoded using an affine advanced motion vector prediction (AMVP) mode; means for constructing an affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, wherein the affine AMVP motion vector predictor list includes at least one or more inherited affine motion vector predictors or one or more constructed affine motion vector predictors, and wherein the affine AMVP motion vector predictor list further includes one or more affine motion vector predictors that cause all control point motion vectors to be equal to a specified motion vector; Means for determining the designated motion vector from a designated motion vector candidate list in the following order, wherein the designated motion vector candidate list is different from the affine AMVP motion vector predictor list: 1) a lower left control point motion vector in a constructed affine motion vector predictor, wherein the constructed affine motion vector predictor is a translation motion vector for predicting a specific control point motion vector of the affine AMVP mode, 2) The upper right control point motion vector in the constructed affine motion vector predictor, 3) The upper left control point motion vector in the constructed affine motion vector predictor, 4) Temporal motion vector predictor, and 5) Zero motion vector; means for determining a control point motion vector for said block of video data from said affine AMVP motion vector predictor list; and Means for encoding the block of video data using the determined control point motion vectors.

40. The device according to claim 39, wherein Means for constructing the affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data comprises: means for inserting said one or more inherited affine motion vector predictors into said affine AMVP motion vector predictor list, if applicable; means for inserting the one or more constructed affine motion vector predictors into the affine AMVP motion vector predictor list, if available, if the number of the one or more inherited affine motion vector predictors is less than a predefined maximum number of the affine AMVP motion vector predictor list; and A component for inserting the one or more affine motion vector predictors that make all control point motion vectors equal to the specified motion vector into the affine AMVP motion vector predictor list if the number of the one or more inherited affine motion vector predictors and the one or more constructed affine motion vector predictors is less than the predefined maximum number of the affine AMVP motion vector predictor list.

41. The apparatus of claim 39, wherein: The means for constructing an affine AMVP motion vector predictor list of the candidate control point motion vectors for the block of video data comprises: Means for constructing an affine AMVP motion vector predictor list of the candidate control point motion vectors for the block of video data without performing a pruning process.

42. A non-transitory computer-readable storage medium storing instructions that, when executed, cause one or more processors to: Receiving a block of video data to be encoded using an affine advanced motion vector prediction (AMVP) mode; Constructing an affine AMVP motion vector predictor list of candidate control point motion vectors for the video data block, wherein: The affine AMVP motion vector predictor list includes at least one or more inherited affine motion vector predictors or one or more constructed affine motion vector predictors, and wherein the affine AMVP motion vector predictor list further includes one or more affine motion vector predictors that make all control point motion vectors equal to a specified motion vector; The designated motion vector is determined from a designated motion vector candidate list in the following order, wherein the designated motion vector candidate list is different from the affine AMVP motion vector predictor list: 1) a lower left control point motion vector in a constructed affine motion vector predictor, wherein the constructed affine motion vector predictor is a translation motion vector for predicting a specific control point motion vector of the affine AMVP mode, 2) The upper right control point motion vector in the constructed affine motion vector predictor, 3) The upper left control point motion vector in the constructed affine motion vector predictor, 4) Temporal motion vector predictor, and 5) Zero motion vector; determining a control point motion vector for the block of video data from the affine AMVP motion vector predictor list; as well as The block of video data is encoded using the determined control point motion vectors.

43. The non-transitory computer-readable storage medium of claim 42, wherein: To construct the affine AMVP motion vector predictor list of candidate control point motion vectors for the block of video data, the instructions cause the one or more processors to: inserting the one or more inherited affine motion vector predictors into the affine AMVP motion vector predictor list, if applicable; if the number of the one or more inherited affine motion vector predictors is less than a predefined maximum number of the affine AMVP motion vector predictor list, inserting the one or more constructed affine motion vector predictors into the affine AMVP motion vector predictor list, if available; as well as If the number of the one or more inherited affine motion vector predictors and the one or more constructed affine motion vector predictors is less than the predefined maximum number of the affine AMVP motion vector predictor list, the one or more affine motion vector predictors that make all control point motion vectors equal to the specified motion vector are inserted into the affine AMVP motion vector predictor list.

44. The non-transitory computer-readable storage medium of claim 42, wherein: To construct an affine AMVP motion vector predictor list of the candidate control point motion vectors for the block of video data, the instructions cause the one or more processors to: An affine AMVP motion vector predictor list of the candidate control point motion vectors for the block of video data is constructed without performing a pruning process.

Images