Symmetric Merge Mode Motion Vector Coding

Abstract

To provide systems, devices and methods for symmetric merge mode motion vector coding.SOLUTION: Symmetric bi-prediction motion vectors (MVs) may be constructed from available candidates in a merge candidate list for regular inter prediction merge mode and / or affine prediction merge mode. Available MV merge candidates may be symmetrically extended or mapped in either direction (e.g., between reference pictures before and after a current picture), for example, when coding a picture that allows bi-directional motion compensation prediction. A symmetric bi-prediction merge candidate may be selected among merge candidates for predicting the motion information of a current prediction unit (PU). The symmetric mapping construction may be repeated by an encoder (e.g., based on a coded index of the MV merge candidate list), for example, to obtain the same merge candidates and coded MV at the encoder.SELECTED DRAWING: Figure 11A

Description

[Technical Field]

[0001] This application relates to symmetric merge mode motion vector coding. [Background technology]

[0002] Cross-reference of related applications This application claims priority to U.S. Provisional Patent Application No. 62 / 816,586, filed on 11 March 2019, entitled “Symmetric Motion Vector Difference Coding,” the entirety of which is incorporated by reference as if it were fully described herein.

[0003] Video coding systems are used to compress digital video signals, for example, to reduce the storage and / or transmission bandwidth required for such signals. Video coding systems may include block-based systems, wavelet-based systems, and / or object-based systems. [Overview of the project]

[0004] Systems, devices, and methods for symmetric merge-mode motion vector coding are described herein. Symmetric bi-pred (bi-prediction) motion vectors (MVs) can be constructed from available candidates in a list of merge candidates for regular interprediction merge modes and / or affine prediction merge modes. Available MV merge candidates can be expanded or mapped symmetrically in either direction (e.g., between reference pictures before and after the current picture) when encoding a picture that enables bi-prediction motion compensation prediction (MCP). A symmetric bi-pred MV can be selected from the merge candidates as the MV for the current prediction unit (PU). Symmetric mapping construction can be repeated (e.g., based on an encoded index in the MV merge candidate list) to obtain the same merge candidate and encoded MV in the decoding device, for example, in the encoding device.

[0005] In the example, a method for determining motion information, including motion vectors (MVs) for predictive units (PUs) in the current picture, may be implemented. This method may be implemented by a device that may include, for example, a computer-readable storage medium storing computer-executable instructions and / or a processor configured to execute computer-executable instructions, wherein the computer-executable instructions, when executed, perform the method for determining motion vectors (MVs) for predictive units (PUs) in the current picture. The method may include the step of obtaining a list of merge candidates for PUs in the current picture (e.g., a step of retrieving, generating, or constructing). The list of merge candidates may include a first merge candidate, which includes a first MV associated with a first reference picture in a first list of reference pictures. A symmetrical merge candidate may be obtained (e.g., constructed) for example, through a symmetrical mapping of the first merge candidate. The symmetrical merge candidate may include a second MV symmetric to the first MV. The symmetrical merge candidate may be associated with a second reference picture in a second list of reference pictures. A symmetrical merge candidate may also be a bidirectional predictive merge candidate and may include a first MV associated with a first reference picture in a first reference picture list and a second MV symmetrical to the first MV associated with a second reference picture in a second reference picture list. Symmetrical merge candidates may be integrated (e.g., added) to a merge candidate list. A merge candidate (e.g., a symmetrical merge candidate) may be selected from a merge candidate list for predicting MVs about PUs.

[0006] The first and second reference pictures may be symmetrical with respect to the current picture. For example, the first and second reference pictures may have the same picture order count (POC) distance from the current picture, for example, in opposite directions.

[0007] The construction of symmetric merge candidates may be based on, for example, whether the picture order count (POC) distance to the current picture is equal to the POC distance between the first reference picture and the current picture, and whether the second reference picture list contains the symmetric reference picture of the first reference picture. In an example, under the condition that the symmetric reference picture exists within the second reference picture list, the first merge candidate may be selected to derive a symmetric merge candidate. The symmetric reference picture is the second reference picture of the symmetric merge candidate.

[0008] Other reference picture lists may not contain symmetric reference pictures. The reference picture with the closest POC distance may be selected as the second reference picture of the symmetric merge candidate. For example, a reference picture within the second reference picture list whose POC distance to the current picture is closest to the POC distance between the first reference picture and the current picture may be selected.

[0009] Motion vector scaling may be applied, for example, to construct the second MV for a symmetric merge candidate. The scaling may be based on the POC distance between the second reference picture and the current picture, and the POC distance between the first reference picture and the current picture.

[0010] In an example, for example, a symmetric merge candidate may be constructed and added to the merge candidate list only when the first merge candidate is a uni-directional prediction merge candidate. In various implementations, for example, a symmetric merge candidate may be constructed and added to the merge candidate list regardless of whether the first merge candidate is a bi-prediction (bi-pred) merge candidate or a uni-prediction merge candidate.

[0011] For example, a determination may be made that the first merge candidate is a bi - directional prediction candidate having a first MV based on a first reference picture in the first reference picture list and a third MV based on a third reference picture in the second reference picture list. The second symmetric merge candidate may be constructed via a symmetric mapping of the first merge candidate. The second symmetric merge candidate may be a fourth MV symmetric to the third MV and may include a fourth MV associated with a fourth reference picture in the first reference picture list. The POC distance between the fourth reference picture and the current picture may be equal to or similar to the POC distance between the third reference picture and the current picture.

[0012] The addition of a symmetric merge candidate to the merge candidate list may be based on, for example, a determination that, prior to adding the symmetric merge candidate to the merge candidate list, the symmetric merge candidate is not redundant with any other merge candidate in the merge candidate list.

[0013] The addition of a symmetric merge candidate to the merge candidate list may be based on, for example, a determination that, prior to adding the symmetric merge candidate to the merge candidate list, adding a merge candidate to the merge candidate list will not exceed at least one of the maximum number of allowed merge candidates and the maximum number of allowed symmetric merge candidates.

[0014] The symmetric merge candidate may be added to the merge candidate list in a specific order, for example, after the non - zero MV merge candidates in the merge candidate list and before any zero MV merge candidates.

[0015] The merge candidates may be regular merge candidates or affine merge candidates. For example, the first merge candidate may include at least two candidate control point MVs (CPMVs), and the symmetrical merge candidate may include at least two symmetrically mapped CPMVs, each symmetrical to at least two CPMVs of the first merge candidate. The at least two symmetrically mapped CPMVs can be derived from the symmetric mapping of at least two CPMVs.

[0016] In the example of a four-parameter affine model, there may be a symmetric mapping of the first and second candidate CPMVs of the first merge candidate to the first symmetric CPMV and second symmetric CPMV of the first merge candidate. For example, four affine candidate CPMV parameters, including spatial transformations of x and y, zoom coefficients, and rotation angles, may be symmetrically mapped to four affine symmetric CPMV parameters, including negative spatial transformations of x and y, inverse zoom coefficients, and negative rotation angles. The first and second symmetric CPMVs can be derived based on the four affine symmetric CPMV parameters.

[0017] In the example of a six-parameter affine model, there may be symmetric mappings of the first, second, and third candidate CPMVs of the first merge candidate to the first symmetric CPMV, second symmetric CPMV, and third symmetric CPMV of the first merge candidate. For example, six affine candidate CPMV parameters, including spatial transformations of x and y, zoom coefficients of x and y, and rotation angles of x and y, may be symmetrically mapped to six affine symmetric CPMV parameters, including negative spatial transformations of x and y, inverse zoom coefficients of x and y, and negative rotation angles of x and y. The first, second, and third symmetric CPMVs can be derived based on the six affine symmetric CPMV parameters.

[0018] The methods described herein may be performed by a decoder. In some examples, the methods described herein or their corresponding methods may be performed by an encoder. A computer-readable medium may contain instructions for causing one or more processors to perform the methods described herein. A computer program product containing instructions may cause one or more processors to perform the methods described herein when the program is executed by one or more processors. [Brief explanation of the drawing]

[0019] [Figure 1A] This is a system diagram illustrating an exemplary communication system in which one or more disclosed embodiments may be implemented. [Figure 1B] This is a system diagram illustrating an exemplary wireless transmit / receive unit (WTRU) that may be used in the communication system illustrated in Figure 1A, according to one embodiment. [Figure 1C] This is a system diagram illustrating an exemplary radio access network (RAN) and an exemplary core network (CN) that may be used in a communication system illustrated in Figure 1A according to one embodiment. [Figure 1D] This is a system diagram illustrating a further exemplary RAN and a further exemplary CN that may be used in the communication system illustrated in Figure 1A according to one embodiment. [Figure 2] This diagram illustrates an example of a block-based video encoder. [Figure 3] This is a diagram illustrating an exemplary video decoder. [Figure 4] This figure shows an example of a system in which various forms and examples can be implemented. [Figure 5] This figure shows exemplary locations for spatial merge candidates. [Figure 6] This figure shows an example of motion vector scaling for time merge candidates. [Figure 7A]This figure shows an example of a control point-based affine motion model that includes an affine model with four parameters. [Figure 7B] This figure shows an example of a control point-based affine motion model that includes an affine model with six parameters. [Figure 7C] This figure shows an example of a control point-based affine motion model that includes affine motion vector fields for each subblock. [Figure 8A] This figure shows exemplary locations of inherited affine motion predictors. [Figure 8B] This figure shows an example of control point motion vector inheritance. [Figure 9] This figure shows exemplary locations for candidate positions for the constructed affine merge mode. [Figure 10] This figure shows an example of motion vector refinement on the decoder side. [Figure 11A] This figure shows an example of constructing a symmetric merge MV candidate for regular movements. [Figure 11B] This figure shows an example of constructing a symmetrical merge MV candidate for affine movement. [Modes for carrying out the invention]

[0020] Here, a detailed description of exemplary embodiments will be provided with reference to various figures. This description provides detailed examples of possible implementations, but it should be noted that the details are intended to be illustrative and do not limit the scope of application in any way.

[0021] Figure 1A illustrates an exemplary communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content by sharing system resources, including wireless bandwidth. For example, the communication system 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), quadrature FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT spread OFDM (ZT UW DTS-s OFDM), unique-word OFDM (UW-OFDM), resource, block-filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0022] As shown in Figure 1A, the communication system 100 may include radio transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, although it will be recognized that the disclosed embodiments assume any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, and 102d may be any type of device configured to operate and / or communicate in a radio environment. For example, WTRU102a, 102b, 102c, and 102d, all of which may be referred to as “station” and / or “STA”, may be configured to transmit and / or receive radio signals and may include user equipment (UE), mobile stations, fixed subscriber units or mobile subscriber units, subscriber-based units, pagers, mobile phones, personal digital assistants (PDAs), smartphones, laptop computers, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial processing chain context and / or an automated processing chain context), consumer electronics devices, devices operating on commercial wireless networks and / or industrial wireless networks, etc. Any of WTRU102a, 102b, 102c, and 102d may be referred to interchangeably with UE.

[0023] The communication system 100 may also include base stations 114a and / or base stations 114b. Each of the base stations 114a and 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, and 102d to facilitate access to one or more communication networks, e.g., CN 106 / 115, the Internet 110, and / or other networks 112. For example, base stations 114a and 114b may be base transceiver stations (BTS), node B, enode B, home node B, home enode B, gNB, NR node B, site controller, access point (AP), wireless router, etc. Although base stations 114a and 114b are each illustrated as single elements, it will be recognized that base stations 114a and 114b may include any number of interconnected base stations and / or network elements.

[0024] Base station 114a may be part of RAN 104 / 113, which may include other base stations and / or network elements (not shown), such as base station controllers (BSCs), radio network controllers (RNCs), relay nodes, etc. Base station 114a and / or base station 114b may be configured to transmit and / or receive radio signals on one or more carrier frequencies, which may be referred to as cells (not shown). These frequencies may be within the licensed spectrum, the unlicensed spectrum, or a combination of the licensed and unlicensed spectrum. A cell may provide coverage for radio services to a particular geographic area that may be relatively fixed or change over time. A cell may be further divided into cell sectors. For example, a cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver per sector of the cell. In one embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and utilize multiple transceivers per sector of the cell. For example, beamforming may be used to transmit and / or receive signals in a desired spatial direction.

[0025] Base stations 114a, 114b may communicate with one or more WTRUs 102a, 102b, 102c, 102d over air interface 116, which may be any suitable radio communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). Air interface 116 may be established using any suitable radio access technology (RAT).

[0026] More specifically, as described above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, base stations 114a and WTRUs 102a, 102b, 102c in RAN 104 / 113 may implement radio technology, such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), and UTRA may establish air interfaces 115 / 116 / 117 using broadband CDMA (WCDMA). WCDMA may include communication protocols, such as High Speed ​​Packet Access (HSPA) and / or Advanced HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​UL Packet Access (HSUPA).

[0027] In one embodiment, base stations 114a and WTRUs 102a, 102b, 102c may implement wireless technology, such as Advanced UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long-Term Evolution (LTE) and / or LTE Advanced (LTE-A) and / or LTE Advanced Pro (LTE-A Pro).

[0028] In one embodiment, the base station 114a and WTRUs 102a, 102b, and 102c may implement wireless technology, such as NR radio access, which may use New Radio (NR) to establish the air interface 116.

[0029] In one embodiment, base station 114a and WTRU 102a, 102b, 102c may implement multiple radio access technologies. For example, base station 114a and WTRU 102a, 102b, 102c may implement both LTE radio access and NR radio, for example, using the dual connectivity (DC) principle. Thus, the air interface utilized by WTRU 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNB and gNB).

[0030] In other embodiments, base stations 114a and WTRUs 102a, 102b, 102c may implement wireless technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Provisional Standard 2000 (IS-2000), Provisional Standard 95 (IS-95), Provisional Standard 856 (IS-856), Global Mobile Communications System (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0031] In Figure 1A, base station 114b may be, for example, a wireless router, home node B, home enode B, or access point, and any suitable RAT may be used to facilitate wireless connectivity in local areas, such as offices, homes, vehicles, campuses, industrial facilities, aerial corridors (e.g., for use by drones), roadways, etc. In one embodiment, base station 114b and WTRU 102c, 102d may establish a wireless local area network (WLAN) by implementing wireless technology, such as IEEE 802.11. In one embodiment, base station 114b and WTRU 102c, 102d may establish a wireless personal area network (WPAN) by implementing wireless technology, such as IEEE 802.15. In another embodiment, base stations 114b and WTRUs 102c, 102d may establish picocells or femtocells using cellular-based RATs (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.). As shown in Figure 1A, base station 114b may have a direct connection to the internet 110. Therefore, base station 114b may not be required to access the internet 110 via CN 106 / 115.

[0032] RAN104 / 113 may communicate with CN106 / 115, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of WTRU102a, 102b, 102c, and 102d. The data may have various quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, and mobility requirements. CN106 / 115 may provide call control, billing services, mobile location-based services, prepaid calls, internet connectivity, video distribution, etc., and / or perform advanced security functions, such as user authentication. Although not shown in Figure 1A, it will be recognized that RAN104 / 113 and / or CN106 / 115 may communicate directly or indirectly with other RANs employing the same RAT as RAN104 / 113 or different RATs. For example, in addition to being connected to RAN104 / 113, which may utilize NR radio technology, CN106 / 115 may also communicate with another RAN (not shown) employing GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0033] CN106 / 115 may also serve as a gateway for WTRU102a, 102b, 102c, and 102d to access PSTN108, the Internet 110, and / or other networks 112. PSTN108 may include a circuit-switched telephone network providing plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices using common communication protocols, such as the Transmit Control Protocol (TCP), User Datagram Protocol (UDP), and / or Internet Protocol (IP) in the TCP / IP Internet Protocol Suite. Network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, network 112 may include another CN connected to one or more RANs, one or more RANs may employ the same RAT as RAN104 / 113 or a different RAT.

[0034] Some or all of the WTRUs 102a, 102b, 102c, and 102d in the communication system 100 may include multimode capability (for example, WTRUs 102a, 102b, 102c, and 102d may include multiple transceivers for communicating with different radio networks on different radio links). For example, WTRU 102c shown in Figure 1A may be configured to communicate with base station 114a which may employ cellular-based radio technology and base station 114b which may employ IEEE 802 radio technology.

[0035] Figure 1B is a system diagram illustrating an exemplary WTRU 102. As shown in Figure 1B, the WTRU 102 may particularly include a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power supply 134, a Global Positioning System (GPS) chipset 136, and / or other peripheral devices 138. It will be recognized that the WTRU 102 may include any subcombinations of the aforementioned elements, while remaining consistent with the embodiment.

[0036] The processor 118 may be a general-purpose processor, a dedicated processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to a transceiver 120, and the transceiver 120 may be coupled to a transmit / receive element 122. Although Figure 1B illustrates the processor 118 and the transceiver 120 as separate components, it will be recognized that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0037] The transmit / receive element 122 may be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In one embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive, for example, IR signals, UV signals, or visible light signals. In another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF signals and optical signals. It will be recognized that the transmit / receive element 122 may be configured to transmit and / or receive any combination of radio signals.

[0038] Although the transmit / receive element 122 is illustrated as a single element in Figure 1B, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) to transmit and receive radio signals over the air interface 116.

[0039] The transceiver 120 may be configured to modulate the signal to be transmitted by the transmit / receive element 122 and to demodulate the signal to be received by the transmit / receive element 122. As described above, the WTRU 102 may have multimode capability. Therefore, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0040] The processor 118 of the WTRU102 may be coupled to a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light-emitting diode (OLED) display unit), and may receive user input data from these. The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. The processor 118 may also access information from any type of suitable memory, such as non-removable memory 130 and / or removable memory 132, and store data in any type of suitable memory. Non-removable memory 130 may include random access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. Removable memory 132 may include a subscriber identification module (SIM) card, a memory stick, a secure digital (SD) memory card, etc. In another embodiment, the processor 118 may access information from memory not physically located in the WTRU 102, such as memory on a server or home computer (not shown), and store data in memory not physically located in the WTRU 102.

[0041] The processor 118 may be configured to receive power from the power supply 134 and distribute and / or control power to other components in the WTRU 102. The power supply 134 can be any suitable device for supplying power to the WTRU 102. For example, the power supply 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), a solar cell, a fuel cell, etc.

[0042] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or instead of, the information from the GPS chipset 136, the WTRU 102 may determine its location by receiving location information from base stations (e.g., base stations 114a, 114b) on the air interface 116 and / or based on the timing of signals received from two or more nearby base stations. It will be recognized that the WTRU 102 may acquire location information by any suitable location determination method, as conforms to the embodiment.

[0043] The processor 118 may be further coupled to other peripheral devices 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality and / or wired or wireless connectivity. For example, the peripheral devices 138 may include an accelerometer, e-compass, satellite transceiver, digital camera (for photos and / or videos), Universal Serial Bus (USB) port, vibration device, television transceiver, hands-free headset, Bluetooth® module, frequency modulation (FM) radio unit, digital music player, media player, video game player module, internet browser, virtual reality and / or augmented reality (VR / AR) device, activity tracker, etc. The peripheral device 138 may include one or more sensors, one or more of which are gyroscopes, accelerometers, Hall effect sensors, magnetometers, orientation sensors, proximity sensors, temperature sensors, time sensors, geolocation sensors, altimeters, light sensors, touch sensors, magnetometers, barometers, gesture sensors, biometric sensors, and / or humidity sensors.

[0044] WTRU102 may include a full-duplex radio (for example, one associated with a particular subframe for both UL (for example, transmission) and downlink (for example, reception)) where the transmission and reception of some or all of the signal may be parallel and / or simultaneous. The full-duplex radio may include an interference management unit that reduces and / or substantially eliminates self-interference either through hardware (e.g., chokes) or through signal processing via a processor (e.g., via a separate processor (not shown) or processor 118). In one embodiment, WRTU102 may include a half-duplex radio (for example, one associated with a particular subframe for either UL (for example, transmission) or downlink (for example, reception)).

[0045] Figure 1C is a system diagram illustrating RAN104 and CN106 according to one embodiment. As described above, RAN104 may employ E-UTRA radio technology to communicate with WTRU102a, 102b, and 102c on the air interface 116. RAN104 may also communicate with CN106.

[0046] RAN104 may include enodes B160a, 160b, and 160c, but it will be recognized that RAN104 may include any number of enodes B, while remaining consistent with the embodiment. Each of enodes B160a, 160b, and 160c may include one or more transceivers for communicating with WTRU102a, 102b, and 102c on the air interface 116. In one embodiment, enodes B160a, 160b, and 160c may implement MIMO technology. Thus, enode B160a may use multiple antennas, for example, to transmit radio signals to and / or receive radio signals from WTRU102a.

[0047] Each of the e-nodes B160a, 160b, and 160c may be associated with a specific cell (not shown) and may be configured to handle wireless resource management decisions, handover decisions, user scheduling in UL and / or DL, etc. As shown in Figure 1C, the e-nodes B160a, 160b, and 160c may communicate with each other over the X2 interface.

[0048] The CN106 shown in Figure 1C may include a Mobility Management Entity (MME) 162, a Serving Gateway (SGW) 164, and a Packet Data Network (PDN) Gateway (i.e., PGW) 166. Although each of the aforementioned elements is illustrated as part of CN106, it should be noted that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0049] The MME162 can be connected to each of the e-nodes B162a, 162b, and 162c within RAN104 via the S1 interface and can act as a control node. For example, the MME162 may be involved in authenticating users of WTRU102a, 102b, and 102c, activating / deactivating bearers, and selecting a specific serving gateway during the initial attachment period of WTRU102a, 102b, and 102c. The MME162 may also provide control plane functionality for switching between RAN104 and other RANs (not shown) employing other radio technologies, such as GSM and / or WCDMA.

[0050] The SGW164 can be connected to each of the e-nodes B160a, 160b, and 160c within RAN104 via the S1 interface. The SGW164 can generally route and forward user data packets to and from WTRU102a, 102b, and 102c. The SGW164 can also perform other functions, such as anchoring the user plane during handover periods between e-nodes B, triggering paging when DL data is available to WTRU102a, 102b, and 102c, and managing and remembering the context of WTRU102a, 102b, and 102c.

[0051] SGW164 may be connected to PGW166, which can provide WTRU102a, 102b, and 102c with access to a packet-switched network, such as the Internet 110, thereby facilitating communication between WTRU102a, 102b, and 102c and IP-enabled devices.

[0052] CN106 may facilitate communication with other networks. For example, CN106 may provide WTRU102a, 102b, and 102c with access to a circuit-switched network, such as PSTN108, thereby facilitating communication between WTRU102a, 102b, and 102c and conventional land-line communication devices. For example, CN106 may include, or communicate with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) acting as an interface between CN106 and PSTN108. Furthermore, CN106 may provide WTRU102a, 102b, and 102c with access to another network 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0053] Although the WTRU is described as a wireless terminal in Figures 1A to 1D, in certain representative embodiments, such a terminal is expected to be able to use a wired communication interface with a communication network (for example, temporarily or permanently).

[0054] In a typical embodiment, the other network 112 may be a WLAN.

[0055] In Infrastructure Basic Service Set (BSS) mode, a WLAN may have access points (APs) for the BSS and one or more stations (STAs) associated with the APs. APs may have access to, or interfaces to, a Distribution System (DS) or another type of wired / wireless network carrying traffic to and from the BSS. Traffic originating outside the BSS and destined for an STA may arrive through the AP and be delivered to the STA. Traffic originating from an STA and destined for a destination outside the BSS may be sent to the AP and delivered to its respective destination. For example, traffic between STAs within the BSS may be sent through the AP if a source STA can send traffic to an AP, and the AP receives and delivers the traffic to a destination STA. Traffic between STAs within the BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be sent between a source and a destination STA having a Direct Link Setup (DLS) (e.g., directly between them). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using Independent BSS (IBSS) mode does not need to have APs, and STAs within IBSS (e.g., all STAs) or STAs using IBSS may communicate directly with each other. The IBSS communication mode is sometimes referred to herein as the “ad hoc” mode of communication.

[0056] When using the 802.11ac infrastructure operating mode or a similar operating mode, an AP may transmit beacons on a fixed channel, such as the primary channel. The primary channel may be of a fixed width (e.g., a wideband of 20 MHz) or a width that is dynamically set via signaling. The primary channel may also be the operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain typical embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. In the case of CSMA / CA, an STA, including the AP (e.g., any STA), may sense the primary channel. If the primary channel is sensed / detected and / or determined to be in use by a particular STA, that STA may retreat. A single STA (e.g., only one station) may transmit at any given time on a given BSS.

[0057] A high-throughput (HT) STA may use a 40 MHz broadband channel for communication, for example, through a combination of a 20 MHz primary channel and adjacent or non-adjacent 20 MHz channels to form a 40 MHz broadband channel.

[0058] Ultra-high throughput (VHT) STAs may support broadband channels of 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz. 40 MHz channels and / or 80 MHz channels may be formed by combining consecutive 20 MHz channels. 160 MHz channels may be formed by combining eight consecutive 20 MHz channels or by combining two non-consecutive 80 MHz channels, the latter of which may be referred to as an 80+80 configuration. In the 80+80 configuration, data may, after channel coding, be passed through a segment parser that can split the data into two streams. Inverse fast Fourier transform (IFFT) processing and time-domain processing may be performed separately for each stream. The streams may be mapped onto two 80 MHz channels, and the data may be transmitted by the source STA. At the receiver of the receiving STA, the operation described above for the 80+80 configuration may be reversed, and the combined data may be sent to media access control (MAC).

[0059] Sub-1 GHz operating modes are supported by 802.11af and 802.11ah. Channel operating bandwidth and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the television white space (TVWS) spectrum, while 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using the non-TVWS spectrum. According to a typical embodiment, 802.11ah may support meter-type control / machine-type communications, such as MTC devices in a macro coverage area. MTC devices may have limited capabilities, including support for certain bandwidths and / or limited bandwidths (e.g., support only for these). MTC devices may include batteries with battery life exceeding thresholds (e.g., for maintaining very long battery life).

[0060] WLAN systems that can support multiple channels and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include a channel that can be designated as the primary channel. The primary channel may have a bandwidth equal to the most common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by the STA that supports the minimum bandwidth operating mode among all STAs operating in the BSS. In the 802.11ah example, even if the AP and other STAs in the BSS support operating modes of 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidths, the primary channel may be 1MHz wide for an STA (e.g., an MTC type device) that supports 1MHz mode (e.g., only 1MHz mode). Carrier sensing and / or network assignment vector (NAV) settings may depend on the state of the primary channel. For example, if the primary channel is in use due to an STA (which only supports 1MHz operating mode) transmitting to an AP, the entire available frequency band may be considered in use, even if a large portion of the frequency band remains idle and could potentially be available.

[0061] In the United States, the available frequency band that can be used by 802.11ah is from 902 MHz to 928 MHz. In South Korea, the available frequency band is from 917.5 MHz to 923.5 MHz. In Japan, the available frequency band is from 916.5 MHz to 927.5 MHz. The total available bandwidth for 802.11ah is from 6 MHz to 26 MHz, depending on the country code.

[0062] Figure 1D is a system diagram illustrating RAN113 and CN115 according to one embodiment. As described above, RAN113 may employ NR radio technology to communicate with WTRU102a, 102b, and 102c on the air interface 116. RAN113 may also communicate with CN115.

[0063] RAN113 may include gNB180a, 180b, and 180c, but it will be recognized that RAN113 may include any number of gNBs, while remaining consistent with the embodiment. Each of gNB180a, 180b, and 180c may include one or more transceivers for communicating with WTRU102a, 102b, and 102c on the air interface 116. In one embodiment, gNB180a, 180b, and 180c may implement MIMO technology. For example, gNB180a and 108b may utilize beamforming to transmit signals to and / or receive signals from gNB180a, 180b, and 180c. Thus, gNB180a may use multiple antennas to transmit radio signals to and / or receive radio signals from WTRU102a, for example. In one embodiment, gNB180a, 180b, and 180c may implement carrier aggregation technology. For example, gNB180a may transmit multiple component carriers to WTRU102a (not shown). A subset of these component carriers may be on an unauthorized spectrum, while the remaining component carriers may be on an authorized spectrum. In one embodiment, gNB180a, 180b, and 180c may implement multipoint coordination (CoMP) technology. For example, WTRU102a may receive coordinated transmissions from gNB180a and gNB180b (and / or gNB180c).

[0064] WTRU102a, 102b, and 102c may communicate with gNB180a, 180b, and 180c using transmissions associated with scalable numerology. For example, OFDM symbol intervals and / or OFDM subcarrier intervals may vary for different transmissions, different cells, and / or different parts of the radio transmission spectrum. WTRU102a, 102b, and 102c may communicate with gNB180a, 180b, and 180c using subframes or transmit time intervals (TTIs) of varying or scalable lengths (e.g., containing varying numbers of OFDM symbols and / or lasting for varying absolute time lengths).

[0065] gNB180a, 180b, and 180c may be configured to communicate with WTRU102a, 102b, and 102c in standalone and / or non-standalone configurations. In a standalone configuration, WTRU102a, 102b, and 102c may communicate with gNB180a, 180b, and 180c without accessing other RANs (e.g., e-nodes B160a, 160b, and 160c). In a standalone configuration, WTRU102a, 102b, and 102c may use one or more of gNB180a, 180b, and 180c as mobility anchor points. In a standalone configuration, WTRU102a, 102b, and 102c may communicate with gNB180a, 180b, and 180c using unauthorized in-band signals. In a non-standalone configuration, WTRU102a, 102b, and 102c may communicate and / or connect with gNB180a, 180b, and 180c while also communicating and / or connecting with another RAN, such as e-nodes B160a, 160b, and 160c. For example, WTRU102a, 102b, and 102c may implement the DC principle to communicate substantially simultaneously with one or more gNB180a, 180b, and 180c and one or more e-nodes B160a, 160b, and 160c. In a non-standalone configuration, e-nodes B160a, 160b, and 160c may serve as mobility anchors for WTRU102a, 102b, and 102c, and gNB180a, 180b, and 180c may provide additional coverage and / or throughput to service WTRU102a, 102b, and 102c.

[0066] Each of the gNB180a, 180b, and 180c may be associated with a specific cell (not shown) and may be configured to handle wireless resource management decisions, handover decisions, user scheduling in UL and / or DL, support for network slicing, dual connectivity, interaction between NR and E-UTRA, routing of user plane data to user plane functions (UPF) 184a and 184b, routing of control plane information to access and mobility management functions (AMF) 182a and 182b, etc. As shown in Figure 1D, the gNB180a, 180b, and 180c can communicate with each other over the Xn interface.

[0067] The CN115 shown in Figure 1D may include at least one AMF182a, 182b, at least one UPF184a, 184b, at least one Session Management Function (SMF)183a, 183b, and optionally, a Data Network (DN)185a, 185b. Although each of the aforementioned elements is illustrated as part of the CN115, it should be recognized that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0068] AMF182a and 182b can be connected to one or more of gNB180a, 180b, and 180c within RAN113 via the N2 interface and can act as control nodes. For example, AMF182a and 182b may be involved in authenticating users of WTRU102a, 102b, and 102c, supporting network slicing (e.g., handling different PDU sessions with different requirements), selecting specific SMF183a and 183b, managing registration areas, terminating NAS signaling, mobility management, etc. Network slicing may be used by AMF182a and 182b to customize CN support for WTRU102a, 102b, and 102c based on the type of services used by WTRU102a, 102b, and 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine-type communications (MTC) access, and so on. The AMF162 may provide control plane functionality for switching between RAN113 and other RANs (not shown) employing other radio technologies, such as LTE, LTE-A, LTE-A Pro, etc., and / or non-3GPP access technologies, such as WiFi.

[0069] SMF183a and 183b may be connected to AMF182a and 182b in CN115 via the N11 interface. SMF183a and 183b may also be connected to UPF184a and 184b in CN115 via the N4 interface. SMF183a and 183b may select and control UPF184a and 184b, and configure traffic routing through UPF184a and 184b. SMF183a and 183b may perform other functions, such as managing and assigning UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing downlink data notifications. PDU session types may be IP-based, non-IP-based, Ethernet®-based, etc.

[0070] UPF184a and 184b may be connected to one or more of gNB180a, 180b, and 180c in RAN113 via the N3 interface, which may provide WTRU102a, 102b, and 102c with access to a packet-switched network, such as the Internet 110, thereby facilitating communication between WTRU102a, 102b, and 102c and IP-enabled devices. UPF184 and 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, and providing mobility anchoring.

[0071] CN115 may facilitate communication with other networks. For example, CN115 may include an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between CN115 and PSTN108, or may communicate with an IP gateway. CN115 may also provide WTRU102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, WTRU102a, 102b, 102c may be connected to local data networks (DN) 185a, 185b via UPF184a, 184b through an N3 interface to UPF184a, 184b and an N6 interface between UPF184a, 184b and DN185a, 185b.

[0072] With regard to Figures 1A to 1D and the corresponding descriptions therein, with respect to one or more of the WTRU102a to d, base stations 114a to b, e-nodes B160a to c, MME162, SGW164, PGW166, gNB180a to c, AMF182a to b, UPF184a to b, SMF183a to b, DN185a to b, and / or any other devices described herein, one or more, or all, of the functions described herein may be performed by one or more emulation devices (not shown). An emulation device may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, an emulation device may be used to test other devices and / or to simulate network and / or WTRU functions.

[0073] Emulation devices may be designed to implement one or more tests of other devices in a laboratory environment and / or an operator network environment. For example, one or more emulation devices may perform one or more or all of the functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices in a communication network. One or more emulation devices may perform one or more or all of the functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. Emulation devices may be directly coupled to another device for test purposes and / or perform tests using over-the-air wireless communication.

[0074] One or more emulation devices may perform one or more functions, including all of them, without being implemented / deployed as part of a wired communication network and / or wireless communication network. For example, emulation devices may be used in test scenarios in a test laboratory and / or an undeployed (e.g., test) wired communication network and / or wireless communication network to implement testing of one or more components. One or more emulation devices may also be test equipment. RF circuits (e.g., including one or more antennas) via direct RF coupling and / or wireless communication may be used by emulation devices to transmit and / or receive data.

[0075] This application describes a wide variety of embodiments, including tools, features, examples, models, approaches, and so on. Many of these embodiments are described with specificity and, in many cases, in a manner that may sound restrictive, at least to illustrate individual characteristics. However, this is for the purpose of clarity in the description and does not limit the application or scope of those embodiments. In practice, all of the different embodiments may be combined and substituted to provide further embodiments. Furthermore, embodiments may also be combined and substituted with embodiments described in earlier applications.

[0076] The embodiments described and envisioned in this application may be implemented in many different forms. Figures 5 to 11 described herein may provide some examples, but other examples are envisioned. The discussion of Figures 5 to 11 is not intended to limit the scope of implementation. At least one of the embodiments generally relates to video encoding and decoding, and at least one other embodiment generally relates to transmitting a generated or encoded bitstream. These embodiments and other embodiments may be implemented as a computer-readable storage medium storing instructions for encoding or decoding video data according to any of the methods, apparatus, or described methods, and / or a computer-readable storage medium storing a bitstream generated according to any of the described methods.

[0077] In this application, the terms “reconstructed” and “decoded” may be used interchangeably, the terms “pixel” and “sample” may be used interchangeably, and the terms “image,” “picture,” and “frame” may be used interchangeably.

[0078] Various methods are described herein, each of which includes one or more steps or actions to achieve the described method. The order and / or use of any particular steps and / or actions may be modified or combined, unless a particular order of steps or actions is required for the proper operation of the method. Furthermore, terms such as “first,” “second,” etc., may be used in various examples to modify elements, components, steps, operations, etc., such as “first decoding” and “second decoding.” The use of such terms does not imply any ordering of the modified operations unless specifically required. For example, in this example, the first decoding does not need to be performed before the second decoding, and may occur, for example, before the second decoding, during the second decoding period, or during a time period that overlaps with the second decoding.

[0079] Various methods and other embodiments described herein may be used to modify modules of the video encoder 100 and decoder 200, such as the decoding module, as shown in Figures 2 and 3. Furthermore, the subject matter disclosed in the specification may apply to any type, format, or version of video encoding, whether existing or future, whether described in standards or recommendations, and any extensions of such standards and recommendations. Unless otherwise stated or technically excluded, the embodiments described herein may be used individually or in combination.

[0080] Various numerical values, such as 6 as the maximum allowable size of the merge list, 4x4 luminance subblocks, 4x4 chrominance subblocks, 1 / 16 fractional precision, a four-parameter affine model, a six-parameter affine model, and so on, are used in the examples described herein. These values ​​and other specific values ​​are for illustrative purposes only, and the embodiments described are not limited to these specific values.

[0081] Figure 2 shows an exemplary video encoder. While variations of the exemplary encoder 200 are conceivable, the encoder 200 is described below for clarity purposes without describing all expected variations.

[0082] Before encoding, the video sequence may undergo encoding preprocessing (201), such as applying a color conversion to the input color picture (e.g., from RGB 4:4:4 to YCbCr 4:2:0), or performing a remapping of the input picture components to obtain a signal distribution that is more resilient to compression (e.g., using histogram equalization of one of the color components). Metadata may be associated with the preprocessing and attached to the bitstream.

[0083] In encoder 200, the picture is encoded by encoder elements as described below. The picture to be encoded is partitioned (202) into units of coding units (CUs). Each unit is encoded using either intra-mode or inter-mode. If a unit is encoded in intra-mode, it performs intra-prediction (260). In inter-mode, motion estimation (275) and compensation (270) are performed. The encoder decides whether to use intra-mode or inter-mode to encode a unit (205), and indicates the intra / inter decision by, for example, a prediction mode flag. The prediction residual is calculated by, for example, subtracting the predicted blocks from the original image blocks (210).

[0084] The predicted residual is then transformed (225) and quantized (230). The quantized transformation coefficients, as well as the motion vector and other syntax elements, are entropy coded (245) to produce the output bitstream. The encoder can skip the transformation and apply quantization directly to the untransformed residual signal. The encoder can bypass both the transformation and quantization, i.e., the residual is encoded directly without the application of either the transformation or quantization process.

[0085] The encoder decodes the encoded blocks to provide a reference for further prediction. The quantized transformation coefficients are inversely quantized (240) and inversely transformed (250) to decode the prediction residuals. The decoded prediction residuals and the predicted blocks are combined (255) to reconstruct the image blocks. An in-loop filter (265) is applied to the reconstructed picture to perform, for example, deblocking / SAO (Sample Adaptive Offset) filtering to reduce encoding artifacts. The filtered image is stored in a reference picture buffer (280).

[0086] Figure 3 shows an example of a video decoder. In the exemplary decoder 300, the bitstream is decoded by decoder elements as described below. The video decoder 300 generally performs a decoding pass which is the reverse of the encoding pass described in Figure 2. The encoder 200 also generally performs video decoding as part of encoding the video data.

[0087] In particular, the decoder input includes a video bitstream, which may be generated by a video encoder 200. The bitstream is first entropy-decoded (330) to obtain transformation coefficients, motion vectors, and other encoded information. Picture partitioning information indicates how the picture is partitioned. Thus, the decoder may partition the picture (335) according to the decoded picture partitioning information. The transformation coefficients are inversely quantized (340) and inversely transformed (350) to decode the prediction residuals. The decoded prediction residuals and predicted blocks are combined (355) to reconstruct the image blocks. The predicted blocks may be obtained (370) from intra-predictions (360) or motion-compensated predictions (i.e., inter-predictions) (375). An in-loop filter (365) is applied to the reconstructed image. The filtered image is stored in a reference picture buffer (380).

[0088] The decoded picture may further undergo post-decoding processing (385), such as reverse color conversion (e.g., conversion from YCbCr 4:2:0 to RGB 4:4:4), or reverse remapping, which performs the reverse of the remapping process performed in pre-encoding processing (201). Post-decoding processing may use metadata derived in pre-encoding processing and signaled in the bitstream.

[0089] Figure 4 shows an example of a system in which various embodiments and examples described herein may be implemented. System 400 may be embodied as a device comprising various components described below and configured to perform one or more of the embodiments described herein. Examples of such devices include, but are not limited to, various electronic devices such as personal computers, laptop computers, smartphones, tablet computers, digital multimedia set-top boxes, digital television receivers, personal video recording systems, connected home appliances, and servers. The elements of System 400 may be embodied individually or in combination in a single integrated circuit (IC), multiple ICs, and / or discrete components. For example, in at least one example, the processing elements and encoder / decoder elements of System 400 are distributed across multiple ICs and / or discrete components. In various examples, System 400 is communicably coupled to one or more other systems or other electronic devices, for example, via a communication bus or through dedicated input and / or output ports. In various examples, System 400 is configured to implement one or more of the embodiments described in this document.

[0090] System 400 includes at least one processor 410 configured to execute instructions loaded into processor 410, for example, to implement various embodiments described in this document. Processor 410 may include embedded memory, input / output interfaces, and various other circuit configurations as known in the Art. System 400 includes at least one memory 420 (e.g., volatile memory devices and / or non-volatile memory devices). System 400 includes a storage device 440, which may include, but is not limited to, electrically erasable programmable read-only memory (EEPROM), read-only memory (ROM), programmable read-only memory (PROM), random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), flash memory, magnetic disk drives, and / or optical disk drives, as well as non-volatile and / or volatile memory. Storage device 440 may, in non-limiting examples, include internal storage devices, accessory storage devices (including removable and non-removable storage devices), and / or network-accessible storage devices.

[0091] System 400 includes, for example, an encoder / decoder module 430 configured to process data to provide encoded or decoded video, the encoder / decoder module 430 of which may include its own processor and memory. The encoder / decoder module 430 represents a module that may be included in the device to perform encoding and / or decoding functions. As is known, the device may include one or both of the encoding and decoding modules. The encoder / decoder module 430 may also be implemented as a separate element of System 400, or it may be incorporated into the processor 410 as a combination of hardware and software, as is known to those skilled in the art.

[0092] Program code to be loaded into the processor 410 or encoder / decoder 430 to perform the various embodiments described herein may be stored in the storage device 440 and subsequently loaded into memory 420 for execution by the processor 410. According to various examples, one or more of the processor 410, memory 420, storage device 440, and encoder / decoder module 430 may store one or more of various items during the execution period of the processes described herein. Such stored items may include, but are not limited to, input video, decoded video or portions of decoded video, bitstreams, matrices, variables, and intermediate or final results from the processing of equations, formulas, operations, and operational logic.

[0093] In some examples, the internal memory of the processor 410 and / or the encoder / decoder module 430 is used to store instructions and to provide working memory for processing required during encoding or decoding. However, in other examples, memory outside the processing device (for example, the processing device may be either the processor 410 or the encoder / decoder module 430) is used for one or more of these functions. The external memory may be memory 420 and / or storage device 440, for example, dynamic volatile memory and / or non-volatile flash memory. In some examples, the external non-volatile flash memory is used, for example, to store the television's operating system. In at least one example, high-speed external dynamic volatile memory, such as RAM, is used as working memory for video encoding and decoding operations.

[0094] Inputs to the elements of system 400 may be provided through various input devices, as shown in block 445. Such input devices include, but are not limited to, (i) a radio frequency (RF) section that receives RF signals wirelessly transmitted by a broadcaster, for example, (ii) a component (COMP) input terminal (or a set of COMP input terminals), (iii) a universal serial bus (USB) input terminal, and / or (iv) a high-resolution multimedia interface (HDMI) input terminal. Other examples not shown in Figure 4 include composite video.

[0095] In various examples, the input device of block 445 has associated input processing elements as known in the art. For example, the RF portion may be associated with elements suitable for (i) selecting a desired frequency (also referred to as selecting a signal or bandwidth-limiting a signal to a frequency band), (ii) down-converting the selected signal, (iii) again bandwidth-limiting to a narrower frequency band in order to select a signal frequency band (e.g., which may be referred to as a channel in certain examples), (iv) demodulating the down-converted and bandwidth-limited signal, (v) performing error correction, and (vi) demultiplexing to select a desired stream of data packets. The RF portion of various examples includes one or more elements for performing these functions, e.g., frequency selectors, signal selectors, bandwidth limiters, channel selectors, filters, downconverters, demodulators, error correctors, and demultiplexers. The RF portion may include a tuner that performs various of these functions, including, for example, down-converting the received signal to a lower frequency (e.g., an intermediate frequency or a frequency near the baseband), or to the baseband. In one example set-top box, the RF section and its associated input processing elements receive an RF signal transmitted over a wired (e.g., cable) medium, filter it to a desired frequency band, downconvert it, and filter it again to perform frequency selection. Various examples involve rearranging the order of the elements described above (and others), removing some of these elements, and / or adding other elements that perform similar or different functions. Adding elements can include inserting elements between existing elements, such as inserting amplifiers and analog-to-digital converters. In various examples, the RF section includes an antenna.

[0096] Furthermore, the USB terminal and / or HDMI terminal may include their respective interface processors for connecting the system 400 to other electronic devices via USB and / or HDMI connections. It should be understood that various aspects of input processing, such as Reed-Solomon error correction, may be implemented, for example, in a separate input processing IC or within the processor 410, as needed. Similarly, aspects of USB interface processing or HDMI interface processing may be implemented, for example, in a separate interface IC or within the processor 410, as needed. The demodulated, error-corrected, and demultiplexed stream is provided to various processing elements, for example, the processor 410 and an encoder / decoder 430 that operates in conjunction with memory and storage elements to process the data stream as needed for presentation on an output device.

[0097] Various elements of system 400 may be provided within an integrated housing. Within the integrated housing, the various elements may be interconnected using an internal bus known in the art, such as an inter-IC (I2C) bus, wiring, and printed circuit board, and may transmit data between the various elements.

[0098] System 400 includes a communication interface 450 that enables communication with other devices via a communication channel 460. The communication interface 450 may, but is not limited to, include transceivers configured to transmit and receive data on the communication channel 460. The communication interface 450 may, but is not limited to, a modem or a network card, and the communication channel 460 may be implemented, for example, in a wired and / or wireless medium.

[0099] In various examples, data is streamed to system 400 or otherwise provided using a wireless network such as a Wi-Fi network, e.g., IEEE 802.11 (IEEE refers to the Institute of Electrical and Electronics Engineers). In these examples, the Wi-Fi signal is received on a communication channel 460 and a communication interface 450 adapted for Wi-Fi communication. In these examples, communication channel 460 is typically connected to an access point or router that provides access to an external network, including the Internet, to enable streaming of applications and other over-the-top communications. In other examples, the streamed data is provided to system 400 using a set-top box that distributes the data over the HDMI connection of input block 445. Yet another example provides the streamed data to system 400 using the RF connection of input block 445. As shown above, various examples provide data using non-streaming methods. Also, various examples use wireless networks other than Wi-Fi, e.g., cellular networks or Bluetooth networks.

[0100] System 400 can provide output signals to various output devices, including a display 475, a speaker 485, and other peripheral devices 495. In various examples, the display 475 includes, for example, one or more of a touchscreen display, an organic light-emitting diode (OLED) display, a curved display, and / or a foldable display. The display 475 may be for a television, tablet, laptop, cell phone (mobile phone), or other device. The display 475 may be integrated with other components (for example, in a smartphone) or separate (for example, an external monitor for a laptop). Other peripheral devices 495, in various examples of the example, include one or more of a standalone digital video disc (or digital multipurpose disc) (for both terms, DVD), a disc player, a stereo system, and / or a lighting system. Various examples use one or more peripheral devices 495 that provide functions based on the output of System 400. For example, a disc player performs the function of playing the output of System 400.

[0101] In various examples, control signals are communicated between the system 400 and the display 475, speaker 485, or other peripheral devices 495 using signaling such as AV Link, Consumer Electronics Control (CEC), or other communication protocols that enable inter-device control with or without user intervention. Output devices may be coupled to the system 400 in a communicative manner via dedicated connections through their respective interfaces 470, 480, and 490. Alternatively, output devices may be connected to the system 400 using a communication channel 460 via a communication interface 450. The display 475 and speaker 485 may be integrated into a single unit together with other components of the system 400, for example, in an electronic device such as a television. In various examples, the display interface 470 includes a display driver, such as a timing controller (TCon) chip.

[0102] For example, if the RF portion of input 445 is part of a separate set-top box, the display 475 and speaker 485 can, alternatively, be separate from one or more other components. In various examples where the display 475 and speaker 485 are external components, the output signal may be provided via a dedicated output connection, such as an HDMI port, a USB port, or a COMP output.

[0103] The example may be executed by computer software implemented by the processor 410 or by hardware, or by a combination of hardware and software. In a non-limiting example, the example may be implemented by one or more integrated circuits. The memory 420 may be of any type appropriate for the technical environment, and in a non-limiting example, may be implemented using any appropriate data storage technology, such as optical memory devices, magnetic memory devices, semiconductor-based memory devices, fixed memory, and removable memory. The processor 410 may be of any type appropriate for the technical environment, and in a non-limiting example, may include one or more of a microprocessor, a general-purpose computer, a dedicated computer, and a processor based on a multi-core architecture.

[0104] Various implementations involve decoding. “Decoding,” as used in this application, can encompass all or part of the processing performed on the received encoded sequence to produce a final output suitable for display, for example. In various examples, such processing typically includes one or more of the processing performed by a decoder, such as entropy decoding, inverse quantization, inverse transform, and differential decoding. In various examples, such processing may, in addition to or alternative to, processing performed by the decoders of the various implementations described herein, such as performing symmetric merge mode MV decoding, generating merge candidate lists, decoding motion vectors (MVs) for motion-compensated predictions (MCPs), generating symmetric merge candidates for regular inter predictions and affine inter predictions, generating history-based MVP (HMVP) merge candidates, performing MV refinement searches for bidirectional prediction MVs (e.g., performing decoder-side motion vector refinement (DMVR)), utilizing lookup tables (LUTs) to solve for affine model parameter values, and / or decoding indices of MVP lists for MVPs and MV differences (MVDs).

[0105] For further examples, in one example, “decoding” refers only to entropy decoding; in another example, “decoding” refers only to differential decoding; and in yet another example, “decoding” refers to a combination of entropy decoding and differential decoding. Whether the phrase “decoding process” is intended to refer specifically to a subset of operations or to a broader decoding process in general becomes clear from the context of the particular description and should be well understood by those skilled in the art.

[0106] Various implementations involve encoding. In a manner similar to the above discussion of "decoding," "encoding" as used in this application can encompass, for example, all or part of the process performed on an input video sequence to create an encoded bitstream. In various examples, such a process includes one or more operations typically performed by an encoder, such as partitioning, differential encoding, transformation, quantization, and entropy encoding. In various examples, such processes include, in addition to or alternatively, processes performed by encoders of various implementations described herein, such as performing symmetric merge mode MV encoding, generating merge candidate lists, encoding motion vectors (MVs) for motion-compensated predictions (MCPs), generating symmetric merge candidates for regular inter-predictions and affine inter-predictions, generating merge candidates for history-based MVPs (HMVPs), performing MV refinement searches for bidirectional predictive MVs, utilizing lookup tables (LUTs) to solve for affine model parameter values, and / or decoding indexes of MVP lists for MVPs and MV differences (MVDs).

[0107] For further examples, in one example, “encoding” refers only to entropy encoding; in another example, “encoding” refers only to differential encoding; and in yet another example, “encoding” refers to a combination of differential and entropy encoding. Whether the phrase “encoding process” is intended to refer specifically to a subset of operations or to a broader encoding process in general will become clear from the context of the particular description and should be well understood by those skilled in the art.

[0108] It should be noted that the syntax elements used herein, such as coding syntax in merge mode (e.g., merge_flag and merge_index) and coding syntax in affine merge mode (e.g., merge_subblock_flag and / or merge_subblock_index), are descriptive terms. Therefore, they do not preclude the use of other syntax element names.

[0109] When a diagram is presented as a flow chart, it should be understood that it also provides a block diagram of the corresponding device. Similarly, when a diagram is presented as a block diagram, it should be understood that it also provides a flow chart of the corresponding method / process.

[0110] Various examples refer to rate-distortion optimization. In particular, during the encoding process, a balance or trade-off between rate and distortion is usually considered, often constraining the computational complexity. Rate-distortion optimization is usually formulated as minimizing a rate-distortion function, which is a weighted sum of rate and distortion. There are various approaches to solving the rate-distortion optimization problem. For example, an approach may be based on a comprehensive test of all encoding options, including all the mode or encoding parameter values ​​to be considered, along with a complete evaluation of their encoding costs after encoding and decoding and the associated distortion of the reconstructed signal. Faster approaches may also be used to reduce encoding complexity, particularly with the calculation of distortion approximated based on the predicted or predicted residual signal rather than the reconstructed signal. A mixture of these two approaches can also be used, for example, by using approximated distortion for only some of the possible encoding options and full distortion for the others. Other approaches evaluate only a subset of the possible encoding options. More generally, many approaches employ one of a wide variety of techniques to perform optimization, but optimization does not necessarily provide a complete evaluation of both the coding cost and the associated distortions.

[0111] The implementations and embodiments described herein may be implemented, for example, in methods or processes, apparatus, software programs, data streams, or signals. Even when an implementation is discussed only in the context of a single form (e.g., discussed only as a method), the implementation of the features discussed may also be implemented in other forms (e.g., apparatus or programs). Apparatus may be implemented, for example, in appropriate hardware, software, and firmware. A method may be implemented, for example, in a processor, where a processor refers to a processing device in general, including, for example, a computer, a microprocessor, an integrated circuit, or a programmable logic device. A processor also includes communication devices, such as computers, cell phones, portable / mobile personal digital assistants ("PDAs"), and other devices that facilitate the communication of information between end users.

[0112] The phrases "one example" or "example" or "one implementation" or "implementation," and any other variations thereof, mean that the specific features, structures, characteristics, etc. described in relation to the example are included in at least one example. Therefore, the phrases "in one example" or "in an example" or "in one implementation" or "in an implementation," and any other variations thereof, appearing in various places throughout this application, do not necessarily all refer to the same example.

[0113] Furthermore, this application may refer to "determining" various types of information. Determining information may include, for example, one or more of the following: estimating information, calculating information, predicting information, or retrieving information from memory. Acquiring may include receiving, retrieving, constructing, generating, and / or determining.

[0114] Furthermore, this application may refer to “accessing” various types of information. Accessing information may include, for example, receiving information, retrieving information (e.g., from memory), storing information, moving information, copying information, computing information, determining information, predicting information, or estimating information.

[0115] Furthermore, this application may refer to "receiving" various types of information. Receiving is intended to be a broad term, just as it is to "accessing." Receiving information may include, for example, accessing information or retrieving information (for example, from memory), one or more of these. Moreover, "receiving" is typically accompanied in some way during an operation such as, for example, storing information, processing information, transmitting information, moving information, copying information, erasing information, calculating information, determining information, predicting information, or estimating information.

[0116] For example, in the cases of "A / B", "A and / or B", and "at least one of A and B", it should be recognized that any use of " / ", "and / or", and "at least one of" below is intended to encompass the selection of only the first listed option (A), only the second listed option (B), or both options (A and B). As a further example, in the cases of "A, B, and / or C" and "at least one of A, B, and C", such usage is intended to encompass the selection of only the first listed option (A), or only the second listed option (B), or only the third listed option (C), or only the first and second listed options (A and B), or only the first and third listed options (A and C), or only the second and third listed options (B and C), or all three options (A, B, and C). This can be extended to the same number of items listed, as will be obvious to those skilled in the art in this and related fields.

[0117] Furthermore, as used herein, the term “signaling” refers, in particular, to indicating something to the corresponding decoder. Encoder signals may include, for example, the size of the merge candidate list, the encoded merge candidate index of the merge MV prediction candidate list, etc. Thus, in the examples, the same parameters are used on both the encoder and decoder sides. Therefore, for example, the encoder can transmit certain parameters to the decoder (explicit signaling) so that the decoder can use the same specific parameters. Conversely, if the decoder already has certain parameters and other parameters, signaling can be used without transmission (implicit signaling) to simply allow the decoder to know and select the specific parameters. Bit saving is achieved in various examples by avoiding the transmission of arbitrary actual functions. It should be recognized that signaling can be achieved in a wide variety of ways. For example, one or more syntax elements, flags, etc., are used in various examples to signal information to the corresponding decoder. The above relates to the verb form of the word "signal," but the word "signal" can also be used as a noun in this specification.

[0118] As will be obvious to those skilled in the art, implementations can produce a wide variety of signals formatted to carry information that can be stored or transmitted. This information may include, for example, instructions for performing a method, or data created by one of the implementations described. For example, a signal may be formatted to carry the bitstream of the example described. Such a signal may be formatted, for example, as an electromagnetic wave (using, for example, the radio frequency portion of the spectrum) or as a baseband signal. Formatting may include, for example, encoding a data stream and modulating a carrier wave with the encoded data stream. The information carried by the signal may be, for example, analog information or digital information. The signal may be transmitted over a wide variety of different wired or wireless links, as is known. The signal may be stored on a processor-readable medium.

[0119] Many examples are described herein. The features of the examples may be provided individually or in any combination across various claim categories and types. Furthermore, the examples may include one or more of the features, devices, or embodiments described herein, individually or in any combination across various claim categories and types.

[0120] Video coding systems can be used to compress digital video signals, which can reduce storage requirements and / or transmission bandwidth for video signals. Video coding systems may include block-based systems, wavelet-based systems, and / or object-based systems.

[0121] Block-based hybrid coding architectures can combine interpicture prediction and intrapicture prediction and transform the coding by entropy coding. One or more coding modes may be implemented (for example, for coding efficiency) by including, for example, one or more of (i) coding structure, (ii) intra prediction, (iii) inter prediction, transformation, quantization and coefficient coding, (iv) in-loop filter, and / or (v) screen content coding.

[0122] The encoding structure may be implemented using multi-type tree block partitioning, such as quadtree, binary tree, and ternary tree partitioning.

[0123] Intra-prediction can be implemented, for example, with 65 angular intra-prediction directions, including one or more of the wide-angle prediction and / or linear model (LM) saturation modes.

[0124] Interpretation can be implemented using, for example, one or more of the following: affine motion models, sub-block temporal motion vector prediction (SbTMVP), adaptive motion vector accuracy, decoder-side motion vector refinement (DMVR), triangular partitioning, combined intra and interpretation (CIIP), merge mode with motion vector difference (MMVD), bi-directional optical flow (BDOF), and / or bi-predictive weighted averaging (BPWA).

[0125] Transformations, quantization, and coefficient coding can be implemented using, for example, one or more of the following: multiple linear transform selections using discrete cosine transform (DCT)2, discrete sine transform (DST)7, and DCT8; dependent quantization using 51 to 63 maximum quantization parameters (QP); and / or modified transform coefficient coding.

[0126] In-loop filtering can be implemented, for example, using a generalized adaptive loop filter (GALF). Screen content coding can be implemented, for example, using intrablock copying (IBC). 360-degree video coding can be implemented, for example, using horizontal wrap-around motion compensation.

[0127] Different MV encoding modes (e.g., merge mode and advanced motion vector prediction (AMVP) mode) can be implemented, for example, to encode motion vectors (MV) for motion-compensated predictions (MCP). In merge mode, encoded MVs from neighboring PUs (e.g., spatially and / or temporally neighboring PUs) can be collected to create a merge MV candidate list. An index to the list can be encoded and / or sent to the decoder. In AMVP mode, MV candidates from neighboring PUs can be used as MV predictors (MVPs), and an additional MV difference (MVD) can be encoded.

[0128] The continuity of motion trajectories may be assumed and utilized (for example, for encoding efficiency) for pictures that enable bidirectional prediction. Symmetric MVD mapping may, for example, encode an MVD for forward prediction and derive an MVD for backward prediction from the forward prediction (for example, via symmetric mapping). Symmetric MVD mapping may be used (for example, in DMVR) to perform MV refinement search of bidirectional prediction MVs (for example, on the decoder side).

[0129] Symmetric mappings can be used in merge-mode MV coding. Merge-mode MV candidates may be collected or constructed. For example, merge candidates may include one or more of the following: coded MVs from spatially neighboring CUs, coded MVs from temporarily juxtaposed CUs, constructed MVs from spatially neighboring CUs (e.g., for affine motion modes), MVs from previously coded CUs, pairwise-averaged MVs from top candidates of an existing merge candidate list, constructed symmetric bidirectional predictive (bi-pred) MVs, and zero MVs.

[0130] A symmetric bi-pred MV can be constructed from available (e.g., existing) candidates in a merge candidate list. Motion continuity can be leveraged, for example, when encoding a picture that enables bi-predation with motion-compensated predictions (MCP) from reference pictures before and after the current picture. For example, when encoding a picture that enables bi-predation, available MV merge candidates can be extended / mapped symmetrically in either direction (e.g., backward or forward between reference pictures). The constructed symmetric bi-pred merge candidate can be used (e.g., in a merge candidate list) as the MV merge candidate selected by the encoder or decoder. For example, if motion continuity holds, a symmetric bi-pred MV candidate may be selected (e.g., to encode as the MV for the current PU). The decoder may obtain, for example, an encoded MV by iterating through the symmetric mapping construction implemented by the encoder. The encoded index of the MV merge candidate list is provided to the decoder and used by the decoder to produce, for example, a merged candidate list and / or an encoded MV. Encoding efficiency can be improved without incurring encoding bit costs, for example, by constructing symmetrical bi-pred MVs and adding them to the merge candidate list.

[0131] The methods described herein may be performed by a decoder. In some examples, the methods described herein or their corresponding methods may be performed by an encoder. A computer-readable medium may contain instructions for causing one or more processors to perform the methods described herein. A computer program product may contain instructions that, when the program is executed by one or more processors, cause one or more processors to perform the methods described herein.

[0132] Merge-mode MV coding can be performed (for example, for a coded block (CB) or a unit of prediction (PU)). For example, the MV of a CB or PU can be coded in merge mode or AMVP mode. In merge mode, coded MVs for neighboring PUs can be collected as MV candidates in a merge candidate list (for example, to code the current PU). The index of the candidate list can be coded and sent to the decoder. The decoder can reconstruct the MV candidates (for example, based on the coded index) for use, for example, for the MCP of a PU. In AMVP mode, coded MVs for neighbors can be used as MVPs (for example, in an AMVP candidate list (AMVPCL)). The encoder can code the index of the MVP list and (for example, the remaining) the MV difference (MVD) (for example, for the decoder).

[0133] The merge mode can be used for regular translational motion model-based and / or affine motion model-based MCPs.

[0134] A regular interprediction merge mode can be performed. In a regular interprediction merge mode (e.g., a non-affine translational motion model-based MCP), the merge candidate list may be constructed using, for example (in order), one or more of the following types of candidates: spatial MVPs from spatially neighboring coding units (CUs), temporal MVPs from juxtaposed CUs, history-based MVPs from first-in, first-out (FIFO) tables, pairwise-averaged MVPs, symmetric bi-pred MVs, and / or zero MVs.

[0135] The size of the merge list may be signaled, for example, within the slice header. The merge list may have a maximum size (e.g., the maximum number of candidates). In the example, the maximum size of the merge list may be, for example, 6. Other examples may have different maximums or may not have a maximum number of candidates. An index of the best merge candidate may be encoded, for example, for each CU encoded in merge mode. Merge candidates of different categories may have different generation procedures.

[0136] Merger candidates may include spatial candidates. Spatial merge candidates may be derived. In the example, merge candidates (for example, up to four) may be selected from candidates located in the locations shown in Figure 5.

[0137] Figure 5 shows exemplary locations of spatial merge candidates. The order of derivation may be, for example, A1, B1, B0, A0, and B2. Location B2 may be considered, for example, only if the CUs of locations A1, B1, B0, A0 are not used and / or are intra-encoded. The CUs of locations A1, B1, B0, A0 may not be used, for example, if the CUs of locations A1, B1, B0, A0 belong to another slice or tile, or are otherwise unavailable. One or more of the CUs of locations A1, B1, B0, A0 may not provide an MV candidate for the current CU's merge mode, for example, if one or more of the CUs of locations A1, B1, B0, A0 are available but intra-encoded. Addition of candidates may undergo redundancy checks, for example, after the first candidate (e.g., at location A1) has been added. Redundancy checks can remove redundant candidates (e.g., from a merge candidate list) that have the same motion information. Redundancy checks can also consider selected candidate pairs (e.g., to reduce computational complexity).

[0138] Merger candidates may include temporal candidates. In the example, a temporal MVP (TMVP) candidate (e.g., only one) may be added to the merge candidate list. Temporal merge candidates can be derived. A scaled motion vector (for example, for a temporal merge candidate) may be derived based on a juxtaposed CU belonging to a juxtaposed reference picture. The list of reference pictures used for deriving the juxtaposed CU may be indicated, for example, in a slice header, for example, by explicit signaling. A scaled motion vector for a temporal merge candidate can be obtained, for example, as illustrated by the dotted line in Figure 6.

[0139] Figure 6 shows an example of motion vector scaling for a time merge candidate. The scaled motion vector for a time merge candidate can be scaled, for example, based on the motion vector for a juxtaposed CU, using POC (Picture Order Count) distances tb and td. The POC distance tb may represent the POC difference between the current picture and the reference picture of the current picture. The POC distance td may represent the POC difference between the juxtaposed picture and the reference picture of the juxtaposed picture. The reference picture index for the time merge candidate may be set to equal to zero. The location for the time candidate may be selected, for example, between a juxtaposed center candidate CU and a juxtaposed lower-right CU.

[0140] Merge candidates may include history-based merge candidates. History-based MVP (HMVP) merge candidates may be added to the merge candidate list after, for example, spatial MVP and TMVP merge candidates. Motion information of previously encoded blocks may be stored in a table and / or used as the MVP for the current CU. Previously encoded blocks may or may not be from the immediate neighboring CU. A table with multiple HMVP candidates may be maintained, for example, during the encoding / decoding process. For example, if a different coding tree unit (CTU) row is encountered (for example, for the first time), the table may be reset (for example, by emptying the table). For example, if there is an inter-encoded CU of a non-subblock (for example, for an affine mode), motion information may be added to the last entry in the table (for example, as a new HMVP candidate).

[0141] The HMVP table size S may be limited to the maximum number of table entries. In the example, the HMVP table size S may be set to 6, which may indicate that up to 6 HMVP candidates may be added to the table. For example, when inserting (e.g., new) move candidates into the table, a constrained first-in, first-out (FIFO) rule may be used. Redundancy checks may be applied to determine if identical HMVPs exist in the table. Identical (e.g., redundant) HMVPs may be removed from the table. For example, if a candidate is removed, the HMVP candidate may be moved forward.

[0142] HMVP candidates (for example, in an HMVP table) may be used in the merge candidate list construction process. HMVP candidates (for example, in a table) may be examined (for example, in order) to determine whether an HMVP candidate should be a merge candidate. HMVP candidates may be inserted into the merge candidate list, for example, after TMVP candidates. Redundancy checks may be applied to spatial merge candidates or temporal merge candidates, for example, to determine whether an HMVP candidate is redundant. In the example, the number of redundancy check operations may be reduced.

[0143] Merge candidates may include pairwise average merge candidates. Pairwise average candidates can be generated, for example, by averaging candidates of predefined pairs in an available (e.g., existing) list of merge candidates. A predefined pair may be defined, for example, as {(0, 1), (0, 2), (1, 2), (0, 3), (1, 3), (2, 3)}. The numbers may represent merge indices relative to the list of merge candidates. Averaged motion vectors can be calculated, for example, separately for each reference list. Two motion vectors available in a single reference list (e.g., both) can be averaged, even if, for example, the motion vectors point to different reference pictures. If only one motion vector is available, the motion vector can be used directly. If no motion vector is available, the list may be invalid.

[0144] Merging candidates may include symmetric bi-pred motion vectors. The construction of symmetric bi-pred motion vectors is discussed in more detail below.

[0145] Merger candidates may include zero MVPs. The merge list may not be complete after symmetrical bi-pred MV merge candidates have been added to the merge list. Zero MVPs may be inserted at the end of the merge candidate list, for example, up to the maximum number of merge candidates.

[0146] Affine motion-compensated predictions can be performed. Block-based affine transformation motion-compensated predictions (MCPs) can be applied (as described herein) to many types of motion, such as zoom in / out, rotation, viewpoint movement, and other irregular motions.

[0147] Figures 7A–7C illustrate examples of control point-based affine motion models, including a four-parameter affine model, a six-parameter affine model, and an affine motion vector field (MVF) for each subblock. The affine motion field of a block can be described by motion information from motion vectors of two control points (e.g., four parameters) or three control points (e.g., six parameters).

[0148] For a four-parameter affine motion model (as shown in Figure 7A, for example), the motion vector at the sample location (x, y) within the block can be derived, for example, using Equation 1.

[0149]

number

[0150] For example, in the case of a six-parameter affine motion model (as shown in Figure 7B), the motion vector at the sample location (x, y) within the block can be derived, for example, using Equation 2.

[0151]

number

[0152] Referring to Figures 7A and 7B and Equations 1 and 2, the motion vector of the control point v0 in the upper left corner is (mv 0x , mv 0y ) can be shown by: The motion vector of the control point v1 in the upper right corner is (mv 1x , mv 1y This can be shown by (mv). The motion vector of the control point v2 in the lower left corner is (mv 2x , mv 2y This can be shown by:

[0153] Block-based affine transformation predictions can be applied, for example, to simplify motion-compensated predictions. The motion vector of the central sample of a subblock can be calculated to derive the motion vector for a 4x4 luminance subblock. In the example, as shown in Figure 7C, the motion vector of the central sample of each subblock can be calculated according to Equations 1 and / or 2 to derive the motion vector for each 4x4 luminance subblock, for example. The motion vectors may be rounded to a fractional precision of 1 / 16. Motion-compensated interpolation filters can be applied, for example, to generate predictions for each subblock using the derived motion vectors. The subblock size for the chroma component may be set to, for example, 4x4. The MV of a 4x4 chroma subblock can be calculated, for example, as the average of the MVs of four corresponding 4x4 luminance subblocks.

[0154] For example, there may be multiple affine motion interpretation modes (including, for example, affine merge mode and affine AMVP mode), similar to multiple modes of translational motion interpretation.

[0155] A merge mode may be performed for affine prediction. The affine merge mode may be applied, for example, to CUs with a width and height of 8 or more. In the affine merge mode, the control point MV (CPMV) for the current CU may be generated, for example, based on motion information for spatially neighboring CUs. The number of CPMVP candidates may be limited (for example, to the maximum number of candidates). In the example, there may be one or more (for example, up to 5) CPMVP candidates. An index may be signaled (for example, to the decoder by the encoder) to indicate the CPMVP candidate to be used for the current CU. The affine merge candidate list may include one or more of the following types of CPMV candidates: inherited affine merge candidates that can be exteriord from the CPMV of neighboring CUs, constructed affine merge candidate CPMVPs that can be derived using the translational MV of neighboring CUs, constructed symmetric affine merge candidates that can be derived by a symmetric mapping of existing affine merge candidates, and / or zero MVs.

[0156] Inherited affine merge candidates can be used for affine prediction. The number of inherited affine merge candidates may be limited. In the example, there may be a maximum of two inherited affine candidates in the affine merge candidate list. Inherited affine candidates can be derived, for example, from the affine motion model of neighboring blocks (e.g., blocks from the left neighboring CU and blocks from the upper neighboring CU).

[0157] Figures 8A and 8B illustrate exemplary location and control point motion vector inheritance for inherited affine motion predictors. Figure 8A shows exemplary candidate blocks. In the example (for example, for the left predictor), the scan order may be A0 to A1. In the example (for example, for the upper predictor), the scan order may be B0 to B1 to B2. In the example, the first inherited candidate from each side may be selected. Pruning checks may not be performed between two inherited candidates. In the example (for example, if a neighboring affine CU is identified), the control point motion vectors of the neighboring affine CU may be used, for example, to derive the CPMVP candidate in the affine merge list of the current CU. In the example (for example, if the neighboring lower-left block A is encoded in affine mode, as shown in Figure 8B), motion vectors v2, v3, and v4 may be obtained (for example, for the upper-left, upper-right, and lower-left corners of the CU containing block A). For example, if block A is encoded using a four-parameter affine model, the two CPMVs of the current CU may be calculated according to, for example, v2 and v3. For example, if block A is encoded using a six-parameter affine model, the three CPMVs of the current CU may be calculated according to, for example, v2, v3 and v4.

[0158] The constructed affine candidates can be used for affine prediction. Affine candidates can be constructed, for example, by combining neighboring translational motion information from each control point.

[0159] Figure 9 shows exemplary locations of candidate positions for the constructed affine merge mode. Motion information for control points can be derived from identified spatial and temporal neighbors (as shown, for example, in the example in Figure 9). CPMV k(k=1, 2, 3, 4) can represent the k-th control point. In the example (for example, for CPMV1), the blocks may be checked for availability in order (e.g., block B2, then B3, then A2). The MV of the first available block may be used. In the example (for example, for CPMV2), the blocks may be checked for availability in order (e.g., block B1, then B0). In the example (for example, for CPMV3), the blocks may be checked for availability in order (e.g., block A1, then A0). For example, if TMVP is available, TMVP may be used as CPMV4.

[0160] Affine merge candidates can be constructed based on motion information, for example, after the MVs of four control points have been obtained. Combinations of control point MVs can be used to construct (for example, in order) the following:

[0161] {CPMV1, CPMV2, CPMV3}, {CPMV1, CPMV2, CPMV4}, {CPMV1, CPMV3, CPMV4}, {CPMV2, CPMV3, CPMV4}, {CPMV1, CPMV2}, {CPMV1, CPMV3}

[0162] A combination of three CPMVs can construct a candidate for an affine merge of six parameters. A combination of two CPMVs can construct a candidate for an affine merge of four parameters. For example, if the reference indices of the control points are different, for example, to avoid the motion scaling process, the relevant combination of control point MVs may be discarded.

[0163] The constructed symmetric affine merge candidates can be used for affine prediction. These constructed symmetric affine merge candidates can be derived from symmetric mappings of existing affine merge candidates. The constructed symmetric affine merge candidates are discussed in more detail below.

[0164] Zero MV can be used for affine prediction. For example, after other constructed affine merge candidates have been examined, such as a constructed symmetric affine merge candidate, if the list is still incomplete, a zero MV can be inserted at the end of the affine merge candidate list.

[0165] A symmetric MV difference (MVD) can be performed for bidirectional predictions. The motion vectors in the forward and backward reference pictures may be symmetric, for example, due to the continuity of motion trajectories in bidirectional predictions. The symmetric motion vector difference (MVD) may include an intercoding mode that uses the continuity of motion trajectories in bidirectional predictions. In a symmetric MVD mode, the MVD of reference picture list 1 may be symmetric to the MVD of list 0. In the example, the MVD of reference picture list 0 (e.g., only the MVD of reference picture list 0) may be signaled (e.g., for coding efficiency). The encoded MV for the current picture in a symmetric MVD mode may be derived, for example, using equation 3.

[0166]

number

[0167] The subscript in Equation 3 may indicate reference list 0 or 1. Directions may be indicated by x and y (for example, x may indicate the horizontal direction and y may indicate the vertical direction).

[0168] A symmetric MVD mode may be available for bidirectional prediction if, for example, either of the following is true: (i) reference list 0 contains forward reference pictures and reference list 1 contains backward reference pictures, and / or (ii) reference list 0 contains backward reference pictures and reference list 1 contains forward reference pictures.

[0169] In the example, the reference picture indices in reference lists 0 and 1 do not need to be signaled, for example, in a symmetric MVD mode. The reference picture indices in reference lists 0 and 1 can be derived, for example, in a symmetric MVD mode.

[0170] In the example (for example, if reference list 0 contains forward-referenced pictures and reference list 1 contains backward-referenced pictures), the reference picture index in list 0 may be set to the forward-referenced picture closest to the current picture, and the reference picture index in list 1 may be set to the backward-referenced picture closest to the current picture.

[0171] Symmetric MVD can reduce signaling overhead and / or coding complexity. For example, a symmetric MVD mode can avoid signaling reference picture indices for both reference picture lists. A symmetric MVD mode can signal only one set of MVDs (e.g., only one set of MVDs) for one list (e.g., list 0).

[0172] Decoder-side motion vector refinement (DMVR) may be performed. Bilateral matching (BM)-based decoder-side motion vector refinement may be applied, for example, to improve the accuracy of the MV in merge mode. The refined MV may be searched around the first MV in reference picture list L0 and / or reference picture list L1, for example in bidirectional prediction operation. BM may calculate the distortion between two candidate blocks in reference picture list L0 and list L1.

[0173] Figure 10 shows an example of motion vector refinement on the decoding side. As illustrated in Figure 10, the sum of absolute difference (SAD) between block 1004 and block 1006 can be calculated, for example, based on each MV candidate around the initial MV. The MV candidate with the lowest SAD may become the refined MV and / or may be used to generate a bidirectional predicted signal.

[0174] The refined MV (e.g., derived by the DMVR process) may be used to generate interprediction samples and / or in temporal motion vector prediction for future picture coding. The original MV may be used in the unblocking process and / or in spatial motion vector prediction for future CU coding.

[0175] As shown in Figure 10, the search point may enclose the first MV. The MV offset may follow the MV difference mirroring (e.g., symmetric) rule. The point may be examined by the DMVR (represented by, for example, candidate MV pair (MV0, MV1)) according to Equation 4.

[0176]

number

[0177] MV offset This could, for example, represent the refinement offset between the initial MV and the refined MV in one of the reference pictures. The refinement search range may be, for example, two integer luminance samples from the initial MV. The search complexity can be reduced, for example, by using a fast search method with an early termination trigger.

[0178] Merge mode MV candidates can be constructed for a PU (e.g., enabling bidirectional prediction). The merge mode MV candidates may be constructed, for example, via a symmetric mapping of candidate MVs from one direction to the other (e.g., from a forward reference picture to a backward reference picture and vice versa) (e.g., existing). The merge mode MV candidates may be constructed, for example, for regular inter prediction merge mode and / or affine prediction merge mode. For example, when the motion trajectory is continuous between video frames, symmetric MV candidate construction via symmetric mapping may be used.

[0179] FIG. 11A is a diagram illustrating an example of symmetric merge MV candidate construction for regular motion. In an example (as shown in FIG. 11), the original merge MV candidates (MV x0 , MV y0 ) may use the reference pictures in list 0. The symmetric mapping of the MVs in the other reference picture list 1 may be derived from the original merge MV candidates (MV x0 , MV y0 ). The derived symmetrically mapped MV candidates may be (MV x1 , MV y1 ). The straight lines with short arrows for MVs may indicate the magnitude of the MVs. The straight lines with long arrows may illustrate the motion trajectories between pictures (e.g., from the reference pictures in list 0 to the current picture and / or from the current picture to the reference pictures in list 1). τ0, τ1 may respectively represent the temporal distance (e.g., POC distance) between the reference pictures in list 0 and the current picture, or the temporal distance (e.g., POC distance) between the current picture and the reference pictures in list 1. In the example, the translational motion vectors MV0 and MV1 (e.g., the straight lines with short arrows) may indicate symmetric translational motion vectors (e.g., MV1 = -MV0).

[0180] Symmetric merge candidates can be constructed for regular interpretations (e.g., from available merge candidates). The list of merge candidates (e.g., the list of available merge candidates) may include, for example, one or more of the following: spatially neighboring MVs, temporally juxtaposed MVs, historical MVPs, pairwise mean MVs, and / or zero MVs. In the example, one or more symmetric bidirectional predictive MV candidates may be located, for example, (i) after a non-zero MV and before a zero MV, (ii) after a historical MVP and before a pairwise mean MV, and / or (iii) after a temporally juxtaposed MV and before a historical MVP. The location of symmetric bidirectional predictive MV candidates may depend, for example, on test results. Being located immediately before a zero MV may be the most conservative location.

[0181] Symmetrical merge candidates can be used for PUs that enable bidirectional prediction. For example, symmetrical merge candidates may be used for PUs for tile group type B and / or for B slices / pictures.

[0182] Symmetric MV candidates can be constructed and / or added to based on available (e.g., existing) merge candidates. Exemplary procedures are provided herein for constructing symmetric MV candidates (e.g., based on available merge candidates).

[0183] In the example, the following exemplary procedure may be implemented in the merge candidate list (e.g., starting from the top candidate) for each available (e.g., existing) merge MV candidate (e.g., candidate i).

[0184] Existing merge mode MV candidates in the merge candidate list (e.g., merge candidate i) are horizontal MvCand i,x , vertical MvCand i,yIt may have a predicted reference picture list refPicList, a reference picture index refPicIdx, and a reference picture order count (POC) refPicPoc. A determination may be made as to whether candidate i is a uni-pred MV. A determination may be made (for example, for a uni-pred MV i) as to whether there are reference pictures in a different reference picture list (e.g., list(1-refPicList)) that have the same POC distance between the current picture and the picture list referenced by merge candidate i, and to the current picture, the current tile group, or the current slice. For example, a determination may be made as to whether equation 5 is true. refPicPocCand i -curPicPoc==curPicPoc-refPicPocSym j formula 5 However, refPicPocCand i ,curPicPoc, and refPicPocSym j These can represent the POC of the reference picture of merge candidate i (e.g., the candidate being evaluated), the POC of the current picture / slice, and the POC of the reference picture j from a different reference picture list (e.g., list(1-refPicList)), respectively.

[0185] For example, if symmetric reference pictures with equivalent POCs are contained in different reference picture lists (e.g., list (1-refPicList)), a symmetric bi-pred MV candidate may be created for merge candidate i. The uni-pred merge candidate MV (e.g., merge candidate i) may be represented as refPicList MV. The symmetric bi-pred MV candidate derived from refPicList MV may also be represented as (1-refPicList)MV, and represents the MV in the prediction direction opposite to that of the uni-pred merge candidate MV. The symmetric bi-pred MV candidate may be derived as a symmetric mapping of the uni-pred candidate MV using, for example, equation 6. MvSym i,x =-MvCand i,x,MvSym i,y =-MvCand i,y formula 6

[0186] Symmetric MV candidates may be added to the merge candidate list based on one or more coefficients / references, such as one or more conditions. In the example, a symmetric bi-pred merge candidate may be added to the merge candidate list if (i) the symmetric bi-pred candidate (e.g., the newly created symmetric bi-pred candidate) is not already in the merge candidate list (e.g., not redundant with candidates in the list), (ii) the total number of available merge candidates in the list is less than the maximum number of allowed merge candidates, and (iii) the total number of symmetric merge candidates in the merge candidate list is less than the maximum number of allowed symmetric merge candidates. In the example, for example, if (i), (ii), or (iii) in the example is not true, the symmetric MV candidate may not be added to the merge candidate list.

[0187] A decision may be made as to whether candidate i is a bi-pred MV. In the example (for example, candidate i is a bi-pred MV), the MV of candidate i associated with two reference picture lists may be considered separately as two individual (e.g., different) uni-pred candidates. The aforementioned symmetric mapping procedure for constructing a symmetric bi-pred candidate (e.g., and for conditionally adding to the merge candidate list) may be applied to each of the two individual uni-pred candidates. The symmetric mapping applied to the two individual uni-pred candidates may produce two different symmetric merge candidates. The decision of whether to add two different symmetric merge candidates may be made individually and applied separately to each symmetric merge candidate, for example.

[0188] The procedure for examining each existing merge candidate in the merge candidate list may be stopped, for example, when the maximum number of merge candidates required and / or the maximum number of symmetrical merge candidates allowed is reached. The next available candidate in the list may be processed, for example, as candidate i is processed as described herein, if the maximum number of merge candidates required and the maximum number of symmetrical merge candidates has not been reached. An added (e.g., newly added) symmetrical candidate may not be processed, for example, as candidate i is processed as described herein.

[0189] In the example, the symmetric reference picture (e.g., equal POC distance) condition may be based on the nearest POC distance rather than an equivalent POC distance, for example, to consider whether a symmetric bi-pred merge candidate should be generated with respect to an existing merge candidate. In the example, the nearest POC may include an equivalent POC (e.g., one with a difference of zero). Whether the conditional POC distance is equal, nearest, or a different distance may depend, for example, on the test results. In the example, examining different (e.g., the other) reference lists as described herein may involve searching for a reference picture that provides the nearest POC distance to the current picture in order to satisfy the equal POC distance condition (e.g., as provided in Equation 5). For example, Equation 7 may be used.

[0190]

number

[0191] In the example (for example, when Equation 7 is used), MV scaling may be applied based, for example, on different POC distances to the current picture. In the example, MV scaling may be applied according to Equation 8.

[0192]

number

[0193] In the example, the maximum number of allowed symmetric merge candidates may be set to, for example, 1 or 2. The maximum number of symmetric merge candidates may depend, for example, on the test results.

[0194] In the example, symmetric merge candidate construction (for example, as described herein) may be applied to, for example, available (e.g., existing) uni-pred merge candidates (e.g., only existing uni-pred merge candidates), bi-pred merge candidates (e.g., only existing bi-pred merge candidates), and / or uni-pred or bi-pred merge candidates (e.g., all existing candidates, whether uni-pred or bi-pred).

[0195] Symmetric merge candidate construction (for example, as described herein) can be performed on the encoder side and / or decoder side. The decoder may, for example, generate the same symmetric merge candidates as constructed by the encoder, based on the encoded merge candidate index of the merge candidate list. Adding symmetric merge candidates to the merge candidate list (for example, as described herein) can improve encoding efficiency without incurring extra encoding and / or signaling costs.

[0196] Encoding syntax in merge mode (e.g., merge_flag and merge_index) may be provided. Constructing a merge candidate list may be provided. In the example, symmetric merge candidates may be added to one or more locations in the merge candidate list (e.g., between pairwise average MV candidates and zero MV candidates).

[0197] Symmetrical merge candidates may be constructed for affine mode predictions. The merge mode may be used, for example, for affine mode MCPs. The list of merge candidates for affine modes may differ from the list of merge candidates for regular inter predictions. In the example of affine mode predictions, the merge candidates may include, for example, one or more of inherited affine merge candidates, constructed affine merge candidates, and / or zero MVs. A symmetrical affine merge candidate (for example, constructed as described herein) may be located, for example, after non-zero MV candidates and before zero MV candidates in the list of affine merge candidates.

[0198] Figure 11B shows an example of constructing a symmetric merge MV candidate for affine motion. In the example (for example, as shown in Figure 11B), the original affine merge candidate (e.g., having multiple MVs) may use the reference picture in List 0. The symmetric mapping of the MV in List 1 of the other reference picture can be derived from the original affine merge candidate MV. In the example, the translational motion vectors MV0 and MV1 (e.g., straight lines with short arrows) may represent symmetrical translational motion vectors (e.g., MV1 = -MV0). The rotation arrows represented by rotation angles θ0 and θ1 may represent symmetrical rotational motion vectors (e.g., θ1 = -θ0). The zoom coefficients ρ0 and ρ1 may represent symmetrical zoom motion vectors (e.g., ρ1 = 1 / ρ0). Similar to Figure 11A, τ0 and τ1 may represent the time distance (e.g., POC distance) between the reference picture in List 0 and the current picture, or the time distance (e.g., POC distance) between the current picture and the reference picture in List 1, respectively.

[0199] In the example, the symmetric affine merge candidate construction may be similar to the symmetric merge candidate construction for regular inter prediction. The differences between symmetric mappings for affine modes and regular inter prediction are explained below.

[0200] In the affine mode (for example, for a uni-pred candidate), two or three control point MVs may be used for 4-parameter and 6-parameter affine models, respectively (as described herein, for example). A symmetric mapping (for example, as shown in Equation 6) may be applied to the upper-left control point MV. The upper-left control point MV may represent the same translational motion as the MV in the regular interprediction mode. The MVs for the other (e.g., one or two) control points (e.g., the upper-right and lower-left control points) may follow different symmetric mapping calculations. The MVs for the other one or two control points (e.g., the upper-right and lower-left control points) may represent zoom and / or rotational motion information.

[0201] The affine motion model can be expressed, for example, according to Equation 9.

[0202]

number

[0203] As shown in Equation 9,

[0204]

number

[0205] and

[0206]

number

[0207] These can be the horizontal and vertical components of MV at location (x, y), and d x d y ρ can be a spatial translation, x ρ y θ can be the zoom coefficient. x θ yx can be a rotation angle, and x and y can represent the horizontal and vertical directions, respectively. Equation 9 can represent an affine motion model with six parameters. An affine model with four parameters can be harmonized with Equations 9 and 10. ρ x =ρ y θ x =θ y Formula 10

[0208] For example, in a four-parameter affine model, the MV of two control points can be known from uni-pred MV candidates. The MV of two control points can be known, for example, from the upper left control point 0 at (0,0).

[0209]

number

[0210] , and the upper right control point at (w, 0)

[0211]

number

[0212] It may include, however, w may be the width of CU. Substituting the two locations and MV into Equation 9 and combining it with the assumption of Equation 10, we can obtain Equations 11 and 12.

[0213]

number

[0214] Substituting equation 11 into equation 12 may yield equation 13.

[0215]

number

[0216] In the example, a lookup table (LUT) is used to solve for one or more values ​​of, for example, ρ, sinθ, and / or cosθ, and as a result, the encoder and decoder may produce the same calculation result. In the example, the LUT may be created using Equation 14.

[0217]

number

[0218] As shown in Equation 14, N can be the control precision (e.g., 256), where a = 0...N and b = 1...N. The square brackets used on the right-hand side of Equation 14 may represent rounding to the nearest integer.

[0219] In an example of symmetric mapping to different prediction directions (e.g., opposite prediction directions), the four affine model parameters (d x d y ρ,θ) is (-d x -d y ρ -1 , -θ) may be mapped (for example, symmetrically). The symmetric mapping of the zoom ratio ρ may be the reciprocal of the zoom ratio ρ (for example, ρ1 = 1 / ρ0, see Figure 11). The two corresponding control points MV of the other reference picture list (for example, from the opposite prediction direction) can be derived, for example, as shown in Equations 15 and 16.

[0220]

number

[0221] As shown in Equations 15 and 16,

[0222]

number

[0223] ,

[0224]

number

[0225] This can represent two control points MV from the other prediction direction.

[0226] Starting from Equation 9, the affine motion symmetric mapping process for four parameters (as described herein, for example) can be extended to solve and / or compute the symmetric mapping MV of the lower left control point for a six-parameter affine model. In Equation 17,

[0227]

number

[0228] This can represent the lower left control point at (0, h), where h is the height of the control unit (CU).

[0229] Substituting (0, h) into equation 9 can yield equation 17.

[0230]

number

[0231] In the six-parameter affine model of Equation 9, the (ρ, θ) derived herein in the four-parameter model is (ρ x θ x ) can be, and this represents the zoom ratio and rotation angle along the horizontal direction. Equation 17 is (ρ y θ y This can be used to solve the equation, which represents the zoom ratio and rotation angle along the vertical direction.

[0232] Substituting equation 11 into equation 17 may yield equation 18.

[0233]

Number

[0234] One or more LUTs (applied similarly to the LUTs described herein) may be used to solve one or more of ρ y , sinθ y , and / or cosθ y . A (for example, using one or more LUTs) symmetric mapping may be performed on the model parameters to map from (d x , d y , ρ y , θ y ) to (-d x , -d y , ρ y -1 , -θ y ). The lower left control point MV from the other direction may be provided, for example, by Equation 19.

[0235]

Number

[0236] As presented as an example herein, different symmetric mapping schemes may be used to construct symmetric affine merge candidates and symmetric merge candidates for regular inter prediction. One or more aspects, considerations or variations used for constructing symmetric affine merge candidates and symmetric merge candidates for regular inter prediction may be the same (e.g., identical). Similar considerations or variations may include, for example, one or more of the following, namely, equal (e.g., or the closest) POC distance conditions, the maximum number of allowed symmetric merge candidates, the types of existing merge candidates that may be used to construct symmetric candidates (e.g., only uni-pred, only bi-pred, or both), etc.

[0237] Encoding syntax in affine merge mode (e.g., merge_subblock_flag and merge_subblock_index) may be provided. Constructing an affine merge candidate list may be provided. Symmetric affine merge candidates (e.g., as described herein) may be added to the affine merge candidate list, for example, after the constructed affine merge MV candidates and before the zero MV candidates.

[0238] While the features and elements are described above in specific combinations, those skilled in the art will recognize that each feature or element can be used alone or in any combination with other features and elements. Furthermore, the methods described herein may be implemented in computer programs, software, or firmware embedded in computer-readable media for execution by a computer or processor. Examples of computer-readable media include electrical signals (transmitted via wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital multi-purpose disks (DVDs). Software and associated processors may be used to implement radio frequency transceivers for use in WTRUs, UEs, terminals, base stations, RNCs, or any host computer.

Claims

1. A device for video decoding, For the current picture, obtain a list of merge candidates, including affine merge candidates, for the prediction units (PUs). Based on the affine merge candidates in the merge candidate list, obtain symmetrical affine merge candidates. In order to predict the motion vector (MV) for the PU, the symmetrical affine merge candidate is inserted into the merge candidate list. Based on the prediction of the MV for the PU, the current picture equipped with the PU is decoded. A device equipped with a processor configured in such a way.

2. The device according to claim 1, wherein the symmetrical affine merge candidate is determined based on a first control point associated with the affine merge candidate.

3. The processor is The symmetrical affine merge candidate is determined using a zoom coefficient that is the inverse of the zoom coefficient associated with the second control point of the affine merge candidate. The device according to claim 2, further configured as follows.

4. The aforementioned processor, The symmetrical affine merge candidate is determined using a rotation angle in the opposite direction to the rotation angle associated with the second control point of the affine merge candidate. The device according to claim 2, further configured as follows.

5. The device according to claim 1, wherein the symmetric affine merge candidate exhibits a translational MVD that is symmetric with respect to the motion vector difference (MVD) of the control point associated with the affine merge candidate.

6. A method for video decoding, For the current picture, obtain a list of merge candidates, including affine merge candidates, and Obtaining symmetrical affine merge candidates based on the affine merge candidates in the merge candidate list, To predict the motion vector (MV) for the PU, the symmetrical affine merge candidate is inserted into the merge candidate list, Based on the prediction of the MV for the PU, the current picture equipped with the PU is decoded. Methods that include...

7. The method according to claim 6, wherein the symmetrical affine merge candidate is determined based on a first control point associated with the affine merge candidate.

8. The method described above is: The symmetrical affine merge candidate is determined using a zoom coefficient that is inverse to the zoom coefficient associated with the second control point of the affine merge candidate. Furthermore, the method according to claim 7.

9. The method described above is: The symmetrical affine merge candidate is determined using a rotation angle in the opposite direction to the rotation angle associated with the second control point of the affine merge candidate. The method according to claim 7, further comprising:

10. A device for video encoding, For the current picture, obtain a list of merge candidates, including affine merge candidates, for the prediction units (PUs). Based on the affine merge candidates in the merge candidate list, obtain symmetrical affine merge candidates. In order to predict the motion vector (MV) for the PU, the symmetrical affine merge candidate is inserted into the merge candidate list. Based on the prediction of the MV for the PU, encode the current picture equipped with the PU. A device equipped with a processor configured in such a way.

11. The device according to claim 10, wherein the symmetrical affine merge candidate is determined based on a first control point associated with the affine merge candidate.

12. The processor is The device according to claim 11, further configured to determine the symmetric affine merge candidate using at least one of a zoom coefficient or a rotation angle, wherein the zoom coefficient is inverse to the zoom coefficient associated with the second control point of the affine merge candidate, and the rotation angle is in the opposite direction to the rotation angle associated with the second control point of the affine merge candidate.

13. A method for video encoding, For the current picture, obtain a list of merge candidates, including affine merge candidates, and Obtaining symmetrical affine merge candidates based on the affine merge candidates in the merge candidate list, To predict the motion vector (MV) for the PU, the symmetrical affine merge candidate is inserted into the merge candidate list, Based on the prediction of the MV for the PU, the current picture equipped with the PU is encoded, Methods that include...

14. The method according to claim 13, wherein the symmetrical affine merge candidate is determined based on a first control point associated with the affine merge candidate.

15. The method described above is: The method according to claim 14, further comprising determining the symmetric affine merge candidate using at least one of a zoom coefficient or a rotation angle, wherein the zoom coefficient is inverse to the zoom coefficient associated with the second control point of the affine merge candidate, and the rotation angle is in the opposite direction to the rotation angle associated with the second control point of the affine merge candidate.

Images