Intra prediction using perspective point / vanishing point

Abstract

Systems, methods, and instrumentalities are disclosed for performing intra-prediction with perspectives. For example, a perspective mode may be used. Perspective mode may be used if an angular intra-prediction mode is used. Perspective mode may include prediction using a perspective point. A perspective indication may be used to indicate whether perspective prediction mode is used. The perspective modes may be signaled and / or derived.

Description

INTRA PREDICTION USING PERSPECTIVE POINT / VANISHING POINTCROSS-REFERENCE TO RELATED APPLICATOINS

[0001] The application claims the benefit of European Patent Application Number 23306662.0, filed October 2, 2023, the contents of which are incorporated by reference in their entirety herein.BACKGROUND

[0002] Video coding systems may be used to compress digital video signals, e.g., to reduce the storage and / or transmission bandwidth needed for such signals. Video coding systems may include, for example, block-based, wavelet-based, and / or object-based systems.SUMMARY

[0003] Systems, methods, and instrumentalities are disclosed for performing intra-prediction with perspectives. For example, a perspective mode may be used. Perspective mode may be used if an angular intra-prediction mode is used. Perspective mode may include prediction using a perspective point. A perspective indication may be used to indicate whether perspective prediction mode is used. The perspective modes may be signaled and / or derived.

[0004] A device (e.g., video encoder or video decoder) may use a perspective mode for intra-prediction. For example, the device may determine that an angular intra prediction mode is used for a coding block. The device may (e.g., based on the determination that an angular intra prediction mode is used for the coding block) determine whether to use a perspective mode for the coding block. The device may obtain an indication (e.g., PerspectiveFlag) that indicates a perspective mode. The device may (e.g., based on a determination that the perspective mode is used for the coding block) determine a perspective point associated with the coding block. The perspective point may be used for an encoding and / or decoding function associate with the coding block. The coding block may be encoded and / or decoded based on the determined perspective point. The device (e.g., an encoder) may send in video data, an encoded coding block and an indication (e.g., PerspectiveFlag) that indicates to use the perspective mode for the encoded coding block.

[0005] In examples, a rate distortion (RD) cost determination may be performed, for example, to determine the perspective mode to use. For example, a full RD cost determination may be performed for a list of candidate intra prediction modes. The mode (e.g., perspective mode) that is associated with a lowest RD cost among the candidate intra prediction modes may be selected. For example, the RD cost determination may include a two passes. For example, the first pass may include a determination of a shortlist of a candidate intra prediction modes (e.g., from the list of candidate intra prediction modes) based on a partial RD criteria. The second pass may include a full RD cost determination associated with the shortlist of candidate intra prediction modes.

[0006] In examples, multiple perspective modes may be used. Multiple perspective points (e.g., one for each perspective mode) may be determined.

[0007] A fixed perspective point may be used and / or determined. The fixed perspective point may be determined based on one or more of the following: a most probable modes (MPM) list; a decoder-side intra mode derivation (DIMD) mode; a template-based intra mode derivation and fusion (TIMD) mode; etc.

[0008] Systems, methods, and instrumentalities described herein may involve a decoder. In some examples, the systems, methods, and instrumentalities described herein may involve an encoder. In some examples, the systems, methods, and instrumentalities described herein may involve a signal (e.g., from an encoder and / or received by a decoder). A computer-readable medium may include instructions for causing one or more processors to perform methods described herein. A computer program product may include instructions which, when the program is executed by one or more processors, may cause the one or more processors to carry out the methods described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented.

[0010] FIG. 1 B is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0011] FIG. 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0012] FIG. 1 D is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1 A according to an embodiment.

[0013] FIG. 2 illustrates an example video encoder.

[0014] FIG. 3 illustrates an example video decoder.

[0015] FIG. 4 illustrates an example of a a system in which various aspects and examples may be implemented.

[0016] FIG. 5 illustrates an example of angular prediction of a target block in intra prediction.

[0017] FIG. 6 illustrates an example of perspective prediction of a target block in intra prediction.

[0018] FIG. 7 illustrates an example of defining a perspective point.

[0019] FIG. 8 illustrates an example of perspective points for a square target block.

[0020] FIG. 9 illustrates an example of perspective points for a rectangular target block.

[0021] FIG. 10 illustrates example mirror perspective points.

[0022] FIG. 11 illustrates example prediction with perspective points.

[0023] FIG. 12 illustrates example perspective points at different distances from the target block but associated with the same prediction mode.

[0024] FIG. 13 illustrates an example dead zone for perspective points.

[0025] Fig. 14 illustrates an example of derivation of the angle parameter for the target pixel at position (x,y).

[0026] FIG. 15 illustrates an example of intra prediction with perspective.

[0027] FIG. 16 illustrates an example of intra prediction with perspective.DETAILED DESCRIPTION

[0028] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings.

[0029] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 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), orthogonal 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 multicarrier (FBMC), and the like.

[0030] As shown in FIG. 1A, the communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104 / 113, a ON 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Eachof the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a "station” and / or a "STA”, may be configured to transmit and / or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fl device, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a UE.

[0031] The communications systems 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or the other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0032] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in desired spatial directions.

[0033] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radiofrequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0034] More specifically, as noted above, the communications 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, and the like. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115 / 116 / 117 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink (DL) Packet Access (HSDPA) and / or High-Speed UL Packet Access (HSUPA).

[0035] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved 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).

[0036] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access , which may establish the air interface 116 using New Radio (NR).

[0037] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs 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., a eNB and a gNB).

[0038] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio 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, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0039] The base station 114b in FIG. 1A may be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network(WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106 / 115.

[0040] The RAN 104 / 113 may be in communication with the CN 106 / 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 the WTRUs 102a, 102b, 102c, 102d. The data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106 / 115 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not shown in FIG. 1A, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may be utilizing a NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0041] The CN 106 / 115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or the other networks 112. The PSTN 108 may include circuit-switched telephone networks that provide plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and / or the internet protocol (IP) in the TCP / IP internet protocol suite. The networks 112 may include wired and / or wireless communications networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 / 113 or a different RAT.

[0042] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0043] FIG. 1 B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1 B, the WTRU 102 may 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 source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138, among others. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0044] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. 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 the transceiver 120, which may be coupled to the transmit / receive element 122. While FIG. 1 B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0045] The transmit / receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the 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 an embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0046] Although the transmit / receive element 122 is depicted in FIG. 1 B as a single element, 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) for transmitting and receiving wireless signals over the air interface 116.

[0047] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit / receive element 122 and to demodulate the signals that are received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11 , for example.

[0048] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and / or the removable memory 132. The 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. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0049] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control the power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 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.), solar cells, fuel cells, and the like.

[0050] The processor 118 may also be coupled to the 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 in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and / or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable locationdetermination method while remaining consistent with an embodiment.

[0051] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a Virtual Reality and / or Augmented Reality (VR / AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors, the sensors may be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0052] The WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the UL (e.g., for transmission) and downlink (e.g., for reception) may be concurrent and / or simultaneous. The full duplex radio may include an interference management unit to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).

[0053] FIG. 1C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0054] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a.

[0055] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, and the like. As shown in FIG. 1 C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0056] The CN 106 shown in FIG. 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0057] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0058] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring user planes during inter-eNodeB handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0059] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0060] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers.

[0061] Although the WTRU is described in FIGS. 1A-1 D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0062] In representative embodiments, the other network 112 may be a WLAN.

[0063] A WLAN in Infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have an access or an interface to a Distribution System (DS) or another type of wired / wireless network that carries traffic in to and / or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA. The traffic between STAs within a BSS may be considered and / or referred to as peer-to- peer traffic. The peer-to-peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11e DLS or an 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an "ad-hoc” mode of communication.

[0064] When using the 802.11ac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP. Incertain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented, for example in in 802.11 systems. For CSMA / CA, the STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0065] High Throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.

[0066] Very High Throughput (VHT) STAs may support 20MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. The 40 MHz, and / or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two noncontiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, may be passed through a segment parser that may divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, may be done on each stream separately. The streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration may be reversed, and the combined data may be sent to the Medium Access Control (MAC).

[0067] Sub 1 GHz modes of operation are supported by 802.11 af and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.11 af and 802.11ah relative to those used in 802.11n, and 802.11ac. 802.11af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11 ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11 ah may support Meter Type Control / Machine- Type Communications, such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and / or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0068] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802.11 n, 802.11 ac, 802.11 af, and 802.11 ah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.11 ah, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz,and / or other channel bandwidth operating modes. Carrier sensing and / or Network Allocation Vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available.

[0069] In the United States, the available frequency bands, which may be used by 802.11 ah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11 ah is 6 MHz to 26 MHz depending on the country code.

[0070] FIG. 1 D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 may employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0071] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 108b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0072] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing varying number of OFDM symbols and / or lasting varying lengths of absolute time).

[0073] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs(e.g ., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c may communicate with / connect to gNBs 180a, 180b, 180c while also communicating with / connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non-standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for servicing WTRUs 102a, 102b, 102c.

[0074] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control plane information towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG. 1 D, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0075] The CN 115 shown in FIG. 1 D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of the CN 115, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0076] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of NAS signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b in order to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized WTRUs 102a, 102b, 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 communication (MTC) access, and / or the like. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi.

[0077] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type may be IP-based, non-IP based, Ethernet-based, and the like.

[0078] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 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, providing mobility anchoring, and the like.

[0079] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local Data Network (DN) 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0080] In view of Figures 1A-1 D, and the corresponding description of Figures 1A-1 D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode- B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DN 185a- b, and / or any other device(s) described herein, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functions.

[0081] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and / or in an operator network environment. For example, the one or more emulation devices may perform the one or more, or all, functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. The one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulationdevice may be directly coupled to another device for purposes of testing and / or may performing testing using over-the-air wireless communications.

[0082] The one or more emulation devices may perform the one or more, including all, functions while not being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in a testing scenario in a testing laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0083] This application describes a variety of aspects, including tools, features, examples, models, approaches, etc. Many of these aspects are described with specificity and, at least to show the individual characteristics, are often described in a manner that may sound limiting. However, this is for purposes of clarity in description, and does not limit the application or scope of those aspects. Indeed, all of the different aspects may be combined and interchanged to provide further aspects. Moreover, the aspects may be combined and interchanged with aspects described in earlier filings as well.

[0084] The aspects described and contemplated in this application may be implemented in many different forms. FIGS. 5-16 described herein may provide some examples, but other examples are contemplated. The discussion of FIGS. 5-16 does not limit the breadth of the implementations. At least one of the aspects generally relates to video encoding and decoding, and at least one other aspect generally relates to transmitting a bitstream generated or encoded. These and other aspects may be implemented as a method, an apparatus, a computer readable storage medium having stored thereon instructions for encoding or decoding video data according to any of the methods described, and / or a computer readable storage medium having stored thereon a bitstream generated according to any of the methods described.

[0085] In the present application, the terms "reconstructed” and "decoded” may be used interchangeably, the terms "pixel” and "sample” may be used interchangeably, the terms "image,” "picture” and "frame” may be used interchangeably.

[0086] Various methods are described herein, and each of the methods comprises one or more steps or actions for achieving the described method. Unless a specific order of steps or actions is required for proper operation of the method, the order and / or use of specific steps and / or actions may be modified or combined. Additionally, terms such as "first”, "second”, etc. may be used in various examples to modify an element, component, step, operation, etc., such as, for example, a "first decoding” and a "second decoding”. Use of such terms does not imply an ordering to the modified operations unless specifically required. So, in this example, the first decoding need not be performed before the second decoding, and may occur, for example, before, during, or in an overlapping time period with the second decoding.

[0087] Various methods and other aspects described in this application may be used to modify modules, for example, decoding modules, of a video encoder 200 and decoder 300 as shown in FIG. 2 and FIG. 3. Moreover, the subject matter disclosed herein may be applied, for example, to any type, format or version of video coding, whether described in a standard or a recommendation, whether pre-existing or future- developed, and extensions of any such standards and recommendations. Unless indicated otherwise, or technically precluded, the aspects described in this application may be used individually or in combination.

[0088] Various numeric values are used in examples described the present application, such as (1 / 32), (1 / 64), etc. These and other specific values are for purposes of describing examples and the aspects described are not limited to these specific values.

[0089] FIG. 2 is a diagram showing an example video encoder. Variations of example encoder 200 are contemplated, but the encoder 200 is described below for purposes of clarity without describing all expected variations.

[0090] Before being encoded, the video sequence may go through pre-encoding processing (201), for example, applying a color transform to the input color picture (e.g., conversion from RGB 4:4:4 to YCbCr 4:2:0), or performing a remapping of the input picture components in order to get a signal distribution more resilient to compression (for instance using a histogram equalization of one of the color components). Metadata may be associated with the pre-processing, and attached to the bitstream.

[0091] In the encoder 200, a picture is encoded by the encoder elements as described below. The picture to be encoded is partitioned (202) and processed in units of, for example, coding units (CUs). Each unit is encoded using, for example, either an intra or inter mode. When a unit is encoded in an intra mode, it performs intra prediction (260). In an inter mode, motion estimation (275) and compensation (270) are performed. The encoder decides (205) which one of the intra mode or inter mode to use for encoding the unit, and indicates the intra / inter decision by, for example, a prediction mode flag. Prediction residuals are calculated, for example, by subtracting (210) the predicted block from the original image block.

[0092] The prediction residuals are then transformed (225) and quantized (230). The quantized transform coefficients, as well as motion vectors and other syntax elements, are entropy coded (245) to output a bitstream. The encoder can skip the transform and apply quantization directly to the non-transformed residual signal. The encoder can bypass both transform and quantization, i.e., the residual is coded directly without the application of the transform or quantization processes.

[0093] The encoder decodes an encoded block to provide a reference for further predictions. The quantized transform coefficients are de-quantized (240) and inverse transformed (250) to decode prediction residuals. Combining (255) the decoded prediction residuals and the predicted block, an image block is reconstructed. In-loop filters (265) are applied to the reconstructed picture to perform, for example,deblocking / SAO (Sample Adaptive Offset) filtering to reduce encoding artifacts. The filtered image is stored at a reference picture buffer (280).

[0094] FIG. 3 is a diagram showing an example of a video decoder. In example decoder 300, a bitstream is decoded by the decoder elements as described below. Video decoder 300 generally performs a decoding pass reciprocal to the encoding pass as described in FIG. 2. The encoder 200 also generally performs video decoding as part of encoding video data.

[0095] In particular, the input of the decoder includes a video bitstream, which may be generated by video encoder 200. The bitstream is first entropy decoded (330) to obtain transform coefficients, motion vectors, and other coded information. The picture partition information indicates how the picture is partitioned. The decoder may therefore divide (335) the picture according to the decoded picture partitioning information. The transform coefficients are de-quantized (340) and inverse transformed (350) to decode the prediction residuals. Combining (355) the decoded prediction residuals and the predicted block, an image block is reconstructed. The predicted block may be obtained (370) from intra prediction (360) or motion-compensated prediction (i.e., inter prediction) (375). In-loop filters (365) are applied to the reconstructed image. The filtered image is stored at a reference picture buffer (380).

[0096] The decoded picture can further go through post-decoding processing (385), for example, an inverse color transform (e.g. conversion from YCbCr 4:2:0 to RGB 4:4:4) or an inverse remapping performing the inverse of the remapping process performed in the pre-encoding processing (201). The post-decoding processing can use metadata derived in the pre-encoding processing and signaled in the bitstream. In an example, the decoded images (e.g., after application of the in-loop filters (365) and / or after post-decoding processing (385), if post-decoding processing is used) may be sent to a display device for rendering to a user.

[0097] FIG. 4 is a diagram showing an example of a system in which various aspects and examples described herein may be implemented. System 400 may be embodied as a device including the various components described below and is configured to perform one or more of the aspects described in this document. 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. Elements of system 400, singly or in combination, may be embodied in a single integrated circuit (IC), multiple ICs, and / or discrete components. For example, in at least one example, the processing and encoder / decoder elements of system 400 are distributed across multiple ICs and / or discrete components. In various examples, the system 400 is communicatively coupled to one or more other systems, or other electronic devices, via, for example, a communications bus or through dedicated input and / or output ports. In various examples, the system 400 is configured to implement one or more of the aspects described in this document.

[0098] The system 400 includes at least one processor 410 configured to execute instructions loaded therein for implementing, for example, the various aspects described in this document. Processor 410 can include embedded memory, input output interface, and various other circuitries as known in the art. The system 400 includes at least one memory 420 (e.g., a volatile memory device, and / or a non-volatile memory device). System 400 includes a storage device 440, which can include non-volatile memory and / or volatile memory, including, but 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, magnetic disk drive, and / or optical disk drive. The storage device 440 can include an internal storage device, an attached storage device (including detachable and non-detachable storage devices), and / or a network accessible storage device, as non-limiting examples.

[0099] System 400 includes an encoder / decoder module 430 configured, for example, to process data to provide an encoded video or decoded video, and the encoder / decoder module 430 can include its own processor and memory. The encoder / decoder module 430 represents module(s) that may be included in a device to perform the encoding and / or decoding functions. As is known, a device can include one or both of the encoding and decoding modules. Additionally, encoder / decoder module 430 may be implemented as a separate element of system 400 or may be incorporated within processor 410 as a combination of hardware and software as known to those skilled in the art.

[0100] Program code to be loaded onto processor 410 or encoder / decoder 430 to perform the various aspects described in this document may be stored in storage device 440 and subsequently loaded onto memory 420 for execution by processor 410. In accordance with various examples, one or more of processor 410, memory 420, storage device 440, and encoder / decoder module 430 can store one or more of various items during the performance of the processes described in this document. Such stored items can include, but are not limited to, the input video, the decoded video or portions of the decoded video, the bitstream, matrices, variables, and intermediate or final results from the processing of equations, formulas, operations, and operational logic.

[0101] In some examples, memory inside of the processor 410 and / or the encoder / decoder module 430 is used to store instructions and to provide working memory for processing that is needed during encoding or decoding. In other examples, however, a memory external to 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 the memory 420 and / or the storage device 440, for example, a dynamic volatile memory and / or a non-volatile flash memory. In several examples, an external non-volatile flash memory is used to store the operating system of, for example, a television. In at least oneexample, a fast external dynamic volatile memory such as a RAM is used as working memory for video encoding and decoding operations.

[0102] The input to the elements of system 400 may be provided through various input devices as indicated in block 445. Such input devices include, but are not limited to, (i) a radio frequency (RF) portion that receives an RF signal transmitted, for example, over the air by a broadcaster, (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 Definition Multimedia Interface (HDMI) input terminal. Other examples, not shown in FIG. 4, include composite video.

[0103] In various examples, the input devices of block 445 have associated respective 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 band-limiting a signal to a band of frequencies), (ii) downconverting the selected signal, (iii) band-limiting again to a narrower band of frequencies to select (for example) a signal frequency band which may be referred to as a channel in certain examples, (iv) demodulating the downconverted and band-limited signal, (v) performing error correction, and / or (vi) demultiplexing to select the desired stream of data packets. The RF portion of various examples includes one or more elements to perform these functions, for example, frequency selectors, signal selectors, band-limiters, channel selectors, filters, downconverters, demodulators, error correctors, and demultiplexers. The RF portion can include a tuner that performs various of these functions, including, for example, downconverting the received signal to a lower frequency (for example, an intermediate frequency or a nearbaseband frequency) or to baseband. In one set-top box example, the RF portion and its associated input processing element receives an RF signal transmitted over a wired (for example, cable) medium, and performs frequency selection by filtering, downconverting, and filtering again to a desired frequency band. Various examples rearrange the order of the above-described (and other) elements, remove some of these elements, and / or add other elements performing similar or different functions. Adding elements can include inserting elements in between existing elements, such as, for example, inserting amplifiers and an analog- to-digital converter. In various examples, the RF portion includes an antenna.

[0104] The USB and / or HDMI terminals can include respective interface processors for connecting system 400 to other electronic devices across USB and / or HDMI connections. It is to be understood that various aspects of input processing, for example, Reed-Solomon error correction, may be implemented, for example, within a separate input processing IC or within processor 410 as necessary. Similarly, aspects of USB or HDMI interface processing may be implemented within separate interface ICs or within processor 410 as necessary. The demodulated, error corrected, and demultiplexed stream is provided to various processing elements, including, for example, processor 410, and encoder / decoder 430 operating in combination withthe memory and storage elements to process the datastream as necessary for presentation on an output device.

[0105] Various elements of system 400 may be provided within an integrated housing, Within the integrated housing, the various elements may be interconnected and transmit data therebetween using suitable connection arrangement 425, for example, an internal bus as known in the art, including the Inter- IC (I2C) bus, wiring, and printed circuit boards.

[0106] The system 400 includes communication interface 450 that enables communication with other devices via communication channel 460. The communication interface 450 can include, but is not limited to, a transceiver configured to transmit and to receive data over communication channel 460. The communication interface 450 can include, but is not limited to, a modem or network card and the communication channel 460 may be implemented, for example, within a wired and / or a wireless medium.

[0107] Data is streamed, or otherwise provided, to the system 400, in various examples, using a wireless network such as a Wi-Fi network, for example IEEE 802.11 (IEEE refers to the Institute of Electrical and Electronics Engineers). The Wi-Fi signal of these examples is received over the communications channel 460 and the communications interface 450 which are adapted for Wi-Fi communications. The communications channel 460 of these examples is typically connected to an access point or router that provides access to external networks including the Internet for allowing streaming applications and other over-the-top communications. Other examples provide streamed data to the system 400 using a set-top box that delivers the data over the HDMI connection of the input block 445. Still other examples provide streamed data to the system 400 using the RF connection of the input block 445. As indicated above, various examples provide data in a non-streaming manner. Additionally, various examples use wireless networks other than Wi-Fi, for example a cellular network or a Bluetooth® network.

[0108] The system 400 can provide an output signal to various output devices, including a display 475, speakers 485, and other peripheral devices 495. The display 475 of various examples includes one or more of, for example, 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, a tablet, a laptop, a cell phone (mobile phone), or other device. The display 475 can also be integrated with other components (for example, as in a smart phone), or separate (for example, an external monitor for a laptop). The other peripheral devices 495 include, in various examples, one or more of a stand-alone digital video disc (or digital versatile disc) (DVD, for both terms), a disk player, a stereo system, and / or a lighting system. Various examples use one or more peripheral devices 495 that provide a function based on the output of the system 400. For example, a disk player performs the function of playing the output of the system 400.

[0109] In various examples, control signals are communicated between the system 400 and the display 475, speakers 485, or other peripheral devices 495 using signaling such as AV. Link, Consumer ElectronicsControl (CEC), or other communications protocols that enable device-to-device control with or without user intervention. The output devices may be communicatively coupled to system 400 via dedicated connections through respective interfaces 470, 480, and 490. Alternatively, the output devices may be connected to system 400 using the communications channel 460 via the communications interface 450. The display 475 and speakers 485 may be integrated in a single unit with the other components of system 400 in an electronic device such as, for example, a television. In various examples, the display interface 470 includes a display driver, such as, for example, a timing controller (T Con) chip.

[0110] The display 475 and speakers 485 can alternatively be separate from one or more of the other components, for example, if the RF portion of input 445 is part of a separate set-top box. In various examples in which the display 475 and speakers 485 are external components, the output signal may be provided via dedicated output connections, including, for example, HDMI ports, USB ports, or COMP outputs.

[0111] The examples may be carried out by computer software implemented by the processor 410 or by hardware, or by a combination of hardware and software. As a non-limiting example, the examples may be implemented by one or more integrated circuits. The memory 420 may be of any type appropriate to the technical environment and 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, as non-limiting examples. The processor 410 may be of any type appropriate to the technical environment, and can encompass one or more of microprocessors, general purpose computers, special purpose computers, and processors based on a multi-core architecture, as non-limiting examples.

[0112] Various implementations involve decoding. "Decoding”, as used in this application, can encompass all or part of the processes performed, for example, on a received encoded sequence in order to produce a final output suitable for display. In various examples, such processes include one or more of the processes typically performed by a decoder, for example, entropy decoding, inverse quantization, inverse transformation, and differential decoding. In various examples, such processes also, or alternatively, include processes performed by a decoder of various implementations described in this application, for example, determining that an angular intra prediction mode is used for a coding block, determining that a perspective mode is used for a coding block, determining a perspective point associated with the coding block, decoding the coding block based on the determined perspective point, etc.

[0113] As further examples, in one example "decoding” refers only to entropy decoding, in another example "decoding” refers only to differential decoding, and in 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 generally to the broader decoding process will be clear based on the context of the specific descriptions and is believed to be well understood by those skilled in the art.

[0114] Various implementations involve encoding. In an analogous way to the above discussion about "decoding”, "encoding” as used in this application can encompass all or part of the processes performed, for example, on an input video sequence in order to produce an encoded bitstream. In various examples, such processes include one or more of the processes typically performed by an encoder, for example, partitioning, differential encoding, transformation, quantization, and entropy encoding. In various examples, such processes also, or alternatively, include processes performed by an encoder of various implementations described in this application, for example, determining that an angular intra prediction mode is used for a coding block, determining that a perspective mode is used for a coding block, determining a perspective point associated with the coding block, encoding the coding block based on the determined perspective point, sending in video data an encoded coding block and an indication that indicates to use the perspective mode for the encoded coding block, etc.

[0115] As further examples, in one example "encoding” refers only to entropy encoding, in another example "encoding” refers only to differential encoding, and in another example "encoding” refers to a combination of differential encoding and entropy encoding. Whether the phrase "encoding process” is intended to refer specifically to a subset of operations or generally to the broader encoding process will be clear based on the context of the specific descriptions and is believed to be well understood by those skilled in the art.

[0116] Note that syntax elements as used herein, for example, coding syntax on perspective mode indications, etc., are descriptive terms. As such, they do not preclude the use of other syntax element names.

[0117] When a figure is presented as a flow diagram, it should be understood that it also provides a block diagram of a corresponding apparatus. Similarly, when a figure is presented as a block diagram, it should be understood that it also provides a flow diagram of a corresponding method / process.

[0118] The implementations and aspects described herein may be implemented in, for example, a method or a process, an apparatus, a software program, a data stream, or a signal. Even if only discussed in the context of a single form of implementation (for example, discussed only as a method), the implementation of features discussed can also be implemented in other forms (for example, an apparatus or program). An apparatus may be implemented in, for example, appropriate hardware, software, and firmware. The methods may be implemented in, for example, a processor, which refers to processing devices in general, including, for example, a computer, a microprocessor, an integrated circuit, or a programmable logic device. Processors also include communication devices, such as, for example, computers, cell phones, portable / personal digital assistants ("PDAs"), and other devices that facilitate communication of information between end-users.

[0119] Reference to "one example” or "an example” or "one implementation” or "an implementation”, as well as other variations thereof, means that a particular feature, structure, characteristic, and so forthdescribed in connection with the example is included in at least one example. Thus, the appearances of the phrase "in one example” or "in an example” or "in one implementation” or "in an implementation”, as well any other variations, appearing in various places throughout this application are not necessarily all referring to the same example.

[0120] Additionally, this application may refer to "determining” various pieces of information. Determining the information can include one or more of, for example, estimating the information, calculating the information, predicting the information, or retrieving the information from memory. Obtaining may include receiving, retrieving, constructing, generating, and / or determining.

[0121] Further, this application may refer to "accessing” various pieces of information. Accessing the information can include one or more of, for example, receiving the information, retrieving the information (for example, from memory), storing the information, moving the information, copying the information, calculating the information, determining the information, predicting the information, or estimating the information.

[0122] Additionally, this application may refer to "receiving” various pieces of information. Receiving is, as with "accessing”, intended to be a broad term. Receiving the information can include one or more of, for example, accessing the information, or retrieving the information (for example, from memory). Further, "receiving” is typically involved, in one way or another, during operations such as, for example, storing the information, processing the information, transmitting the information, moving the information, copying the information, erasing the information, calculating the information, determining the information, predicting the information, or estimating the information.

[0123] It is to be appreciated that the use of any of the following “ / ”, "and / or”, and "at least one of, for example, in the cases of “A / B”, "A and / or B” and "at least one of A and B”, is intended to encompass the selection of the first listed option (A) only, or the selection of the second listed option (B) only, or the selection of 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 phrasing is intended to encompass the selection of the first listed option (A) only, or the selection of the second listed option (B) only, or the selection of the third listed option (C) only, or the selection of the first and the second listed options (A and B) only, or the selection of the first and third listed options (A and C) only, or the selection of the second and third listed options (B and C) only, or the selection of all three options (A and B and C). This may be extended, as is clear to one of ordinary skill in this and related arts, for as many items as are listed.

[0124] Also, as used herein, the word "signal” refers to, among other things, indicating something to a corresponding decoder. Encoder signals may include, for example, an encoded coding block, an indication indicating a perspective mode, an indication indicating a perspective point, etc. In this way, in an example the same parameter is used at both the encoder side and the decoder side. Thus, for example, an encoder can transmit (explicit signaling) a particular parameter to the decoder so that the decoder can use the sameparticular parameter. Conversely, if the decoder already has the particular parameter as well as others, then signaling may be used without transmitting (implicit signaling) to simply allow the decoder to know and select the particular parameter. By avoiding transmission of any actual functions, a bit savings is realized in various examples. It is to be appreciated that signaling may be accomplished in a variety of ways. For example, one or more syntax elements, flags, and so forth are used to signal information to a corresponding decoder in various examples. While the preceding relates to the verb form of the word "signal”, the word "signal” can also be used herein as a noun.

[0125] As will be evident to one of ordinary skill in the art, implementations may produce a variety of signals formatted to carry information that may be, for example, stored or transmitted. The information can include, for example, instructions for performing a method, or data produced by one of the described implementations. For example, a signal may be formatted to carry the bitstream of a described example. Such a signal may be formatted, for example, as an electromagnetic wave (for example, using a radio frequency portion of spectrum) or as a baseband signal. The formatting may include, for example, encoding a data stream and modulating a carrier with the encoded data stream. The information that the signal carries may be, for example, analog or digital information. The signal may be transmitted over a variety of different wired or wireless links, as is known. The signal may be stored on, or accessed or received from, a processor- readable medium.

[0126] Many examples are described herein. Features of examples may be provided alone or in any combination, across various claim categories and types. Further, examples may include one or more of the features, devices, or aspects described herein, alone or in any combination, across various claim categories and types. For example, features described herein may be implemented in a bitstream or signal that includes information generated as described herein. The information may allow a decoder to decode a bitstream, the encoder, bitstream, and / or decoder according to any of the embodiments described. For example, features described herein may be implemented by creating and / or transmitting and / or receiving and / or decoding a bitstream or signal. For example, features described herein may be implemented a method, process, apparatus, medium storing instructions, medium storing data, or signal. For example, features described herein may be implemented by a TV, set-top box, cell phone, tablet, or other electronic device that performs decoding. The TV, set-top box, cell phone, tablet, or other electronic device may display (e.g. using a monitor, screen, or other type of display) a resulting image (e.g., an image from residual reconstruction of the video bitstream). The TV, set-top box, cell phone, tablet, or other electronic device may receive a signal including an encoded image and perform decoding.

[0127] Systems, methods, and instrumentalities are disclosed for performing intra-prediction with perspectives. For example, a perspective mode may be used. Perspective mode may be used if an angularintra-prediction mode is used. Perspective mode may include prediction using a perspective point. A perspective indication may be used to indicate whether perspective prediction mode is used. The perspective modes may be signaled and / or derived.

[0128] A device (e.g., video encoder or video decoder) may use a perspective mode for intra-prediction. For example, the device may determine that an angular intra prediction mode is used for a coding block. The device may (e.g., based on the determination that an angular intra prediction mode is used for the coding block) determine whether to use a perspective mode for the coding block. The device may obtain an indication (e.g., PerspectiveFlag) that indicates a perspective mode. The device may (e.g., based on a determination that the perspective mode is used for the coding block) determine a perspective point associated with the coding block. The perspective point may be used for an encoding and / or decoding function associate with the coding block. The coding block may be encoded and / or decoded based on the determined perspective point. The device (e.g., an encoder) may send in video data, an encoded coding block and an indication (e.g., PerspectiveFlag) that indicates to use the perspective mode for the encoded coding block.

[0129] In examples, a rate distortion (RD) cost determination may be performed, for example, to determine the perspective mode to use. For example, a full RD cost determination may be performed for a list of candidate intra prediction modes. The mode (e.g., perspective mode) that is associated with a lowest RD cost among the candidate intra prediction modes may be selected. For example, the RD cost determination may include a two passes. For example, the first pass may include a determination of a shortlist of a candidate intra prediction modes (e.g., from the list of candidate intra prediction modes) based on a partial RD criteria. The second pass may include a full RD cost determination associated with the shortlist of candidate intra prediction modes.

[0130] In examples, multiple perspective modes may be used. Multiple perspective points (e.g., one for each perspective mode) may be determined.

[0131] A fixed perspective point may be used and / or determined. The fixed perspective point may be determined based on one or more of the following: a most probable modes (MPM) list; a decoder-side intra mode derivation (DIMD) mode; a template-based intra mode derivation and fusion (TIMD) mode; etc.

[0132] Systems, methods, and instrumentalities described herein may involve a decoder. In some examples, the systems, methods, and instrumentalities described herein may involve an encoder. In some examples, the systems, methods, and instrumentalities described herein may involve a signal (e.g., from an encoder and / or received by a decoder). A computer-readable medium may include instructions for causing one or more processors to perform methods described herein. A computer program product may includeinstructions which, when the program is executed by one or more processors, may cause the one or more processors to carry out the methods described herein.

[0133] A (e.g., any) target block in intra prediction may have a prediction mode (e.g., one of the specified prediction modes). The angular prediction modes may be associated with different prediction directions. For a prediction mode (e.g., any of those prediction modes), the (e.g., all the) pixels in a target block may be predicted along the same prediction direction. There may be many natural scenes (e.g., architectural video, driving on roads, river cruises, etc.) which may not be modelled efficiently by this sort of constant prediction model, for example, because of the use of perspectives. In these cases, video codecs using the constant prediction model may either do an inefficient prediction, or may partition the block into many smaller blocks (e.g., in a perspective region), e.g., leading to inefficiency in compression performance. Perspective modes for intra prediction may be used, for example, where predictions may be performed using perspective points.

[0134] Intra prediction may be performed using one or more perspective points, which may be referred to as vanishing points. A perspective mode may be used, for example, where a perspective mode may refer to a prediction with a perspective point. The points may be localized along the prediction directions at (e.g., specific) distances from a target block. Similar to the regular prediction directions, the perspective points may be identified by a perspective direction (e.g., unique perspective direction) with respect to the target block. For a given perspective point, a (e.g., every) target pixel may be predicted along a direction joining the target pixel location with the perspective point location. Thus, target pixels in any row or in any column of a block may have different prediction directions. After the prediction, the residual error may be encoded using the subsequent steps of transform coding, quantization, lossless coding of quantized coefficients, etc. The ratedistortion performance may be compared to those of the existing regular prediction modes. The best prediction may be chosen. A perspective indication (e.g., flag) may be used, for example, to indicate if the chosen perspective prediction mode is used. The perspective modes themselves may be signaled (e.g., explicitly signaled) or may be derived (e.g., implicitly derived) from the decoded normal angular prediction mode, from the set of most probable modes (MPMs), or from the decoder-side intra mode derivation (DIM D) modes or the template-based intra mode derivation and fusion (TIMD) modes, etc.

[0135] The intra prediction of a target block may be considered.. The pixels in the target block may be predicted, for example, based on multiple (e.g., two) arrays of reference samples (e.g., which may include already decoded pixels on the left and above the block). Several angular and multiple (e.g., two) non-angular prediction modes may be defined for that purpose. For an angular mode (e.g., as shown in FIG. 5), the (e.g., all the) target pixels may be predicted in the same direction, for example which may be the prediction direction associated with the prediction mode. The reference samples lying in the direction of prediction may be used as predictors for the target pixels, for example, either as direct copy or with interpolation.

[0136]

[0137] FIG. 5 illustrates an example of angular prediction of a target block in intra prediction. As shown in FIG. 5, the (e.g., all the) target pixels may have the same prediction direction.

[0138] This model of constant prediction direction for a target block of pixels may be used, for example, if (e.g., when) the frame consists of foreground objects without much 3D perspective.

[0139] Some or all parts of a frame may have perspectives, for example, a frame containing natural scenes (e.g., because the 3D nature of the world may have perspective). Perspectives may be common, for example, in video sequences having walls, ceilings, etc. (e.g., as in architectural video, or video sequences shot inside rooms, or containing scenes of driving on roads, river cruises, etc.). In those scenarios with perspective the constant prediction direction prediction model may not be efficient. As shown in FIG. 6, the (e.g., all the) target pixels in a block may have different prediction directions, for example, depending on the direction of perspective. In these cases, video codecs using the constant prediction model may either do an inadequate prediction leading to other prediction types (e.g., such as the Template Based Intra Prediction (IntraTMP), Intra Block Copy (IBC), blended prediction as in Decoder Side Intra Mode Derivation (DIMD), Template Based Intra Mode Derivation and Fusion (TIMD), Spatial Geometric Partition Mode (SGPM), etc.) or partition the block into many smaller blocks in a perspective region (e.g., which may lead to inefficiency in compression performance).

[0140] FIG. 6 illustrates an example of perspective prediction of a target block in intra prediction. Target pixels in a row or column may have different prediction directions. As shown in FIG. 6, the perspective point may be on top of the block.

[0141] Perspective modes may be used for intra prediction where predictions are performed using perspective points. Perspective mode (PM) and Perspective point (PP) may be enabled, used, and / or provided.

[0142] Angular modes may be specified (e.g., 65 regular angular modes and 28 wide angular modes). Out of these modes, some modes (e.g., only 65 modes) may be possible for a (e.g., any) target block depending on its aspect ratio. The angular modes may be also called directional modes (e.g., as each mode may be associated with a prediction direction). The regular angular modes may be associated with prediction directions that span the angle range from 45 degrees to -135 degrees whereas the wide angular modes may be associated with some directions beyond this angle range. A square shaped target block (e.g., a block in which height = width) may have a regular angular mode (e.g., any of 65 regular angular modes), whereas a rectangle shaped target block (e.g., a block in which height > width, or height < width) may have a contiguous angular mode (e.g., any of 65 contiguous angular modes consisting of some regular angular modes and some wide angular modes). The modes associated with directions below the diagonal direction (e.g., thedirection from top left towards bottom right along -45 degrees) may be referred to as horizontal modes and the modes associated with directions above the diagonal direction may be referred to as vertical modes.

[0143] A perspective mode (PM) may be considered as an angular mode with perspective prediction. The prediction may be made using a perspective point (PP) (e.g., vanishing point), which may be located along the direction associated with the angular mode at a specified distance from a target block (e.g., as shown in FIG. 7).

[0144] FIG. 7 illustrates an example of defining a perspective point. For a given prediction mode, the perspective point may be (e.g., may lie) at the intersection of prediction direction at the center of the target block with a line parallel to the side of the block at an offset distance. For vertical modes, the line may be horizontal, and for horizontal modes, the line may be vertical. The offset distances of the line from the target block may be defined as vertical and horizontal perspective distances. H and W may denote the height and width of the target block. In examples, the vertical and horizontal perspective distances may be equal (e.g., as shown in FIG. 7).

[0145] A perspective point (PP) may be defined as the intersection point of the prediction direction (e.g., prediction direction associated with the mode) at the center of a target block with a straight line parallel to the side of the block at an offset distance. For vertical prediction modes, the line may be horizontal at offset distance dy, and for horizontal modes, the line may be vertical at offset distance dx (e.g., as shown in the FIG. 7). For example, dx and dy may include the horizontal and vertical perspective distances, respectively. The perspective point associated with the mode may be denoted as Pm, for example, if the prediction mode index is m.

[0146] the applicable prediction directions may span the range from 45 degrees to -135 degrees (e.g., for a square target block). As shown in FIG. 8, there may be a perspective point defined (e.g., uniquely defined) that may corresponding to a (e.g., each) prediction mode. The PPs associated with vertical modes may be referred to as vertical PPs and PPs associated with horizontal modes may be referred to as horizontal PPs. For example, associated with 33 vertical modes, there may be 33 vertical PPs. For example, associated with 32 horizontal modes, there may be 32 horizontal PPs. The PPs may lie on a square, for example, if dx and dy are equal (e.g., chosen to be equal), as shown in FIG. 8.

[0147] FIG. 8 illustrates an example of perspective points for a square target block. There may be 33 vertical PPs and 32 horizontal PPs corresponding to 33 vertical and 32 horizontal angular modes. In examples, the horizontal perspective and vertical perspective distances may be equal.

[0148] The number of vertical and horizontal modes may depend on the shape of the block (e.g., for a rectangular block), for example, as there may be some wide angular modes besides the regular angular modes. The modes may be defined as vertical or horizontal, for example, depending on if the associatedprediction direction is greater or less than -45 degrees. The placement of the PPs may not be on a rectangle even if dx and dy are chosen such that their ratio (dx / dy) equals the aspect ratio of the block (e.g., (W / H)). The PPs may be defined (e.g., uniquely defined) by the prediction direction and the offset distance (e.g., as shown in FIG. 9. The PPs may be placed (e.g., all be placed) on the outer rectangle by changing some horizontal PPs to vertical PPs by finding the intersection points with the top horizontal line in this example, or by changing some vertical PPs to horizontal PPs by finding the intersection points with the left vertical line (e.g., for a tall rectangular block, that is, when height > width).

[0149] FIG. 9 illustrates an example of perspective points for a rectangular target block. Here the perspective distances may be chosen so that their ratio equals the aspect ratio of the block. There may be 65 perspective points associated with 65 angular modes.

[0150] For a (e.g., any) perspective point Pm, a mirror perspective point P’mmay be defined. The mirror perspective point may be located on the opposite side of the block. The mirror PP may be obtained by extending the prediction direction through the center of the target block and identifying its intersection with the line parallel to the top or the left line (e.g., as shown in FIG. 10). The mirrors of vertical PPs may be vertical. Similarly, the mirrors of horizontal PPs may be horizontal. To distinguish between the two pairs, they may be referred to as vertical up and vertical down PPs, horizontal left and horizontal right PPs, respectively. The mirror of P2 may be Pee and vice versa.

[0151] FIG. 10 illustrates example mirror perspective points. Vertical up and vertical down PPs may be mirrors. Horizontal left and horizontal right PPs may be mirrors.

[0152] The prediction for a target block may be made (e.g., may be always made) using the reference samples on the top and the left, for example, irrespective of the location of the perspective point. FIG. 11 shows examples of perspective prediction if the PP and its mirror PP are on the purely vertical direction (e.g., mode 50). The prediction direction for a (e.g., any) target pixel may be from the PP towards itself (e.g., if the PP is on top) or from itself towards the PP (e.g., if the PP is on the bottom). For horizontal prediction modes, the case may be analogous depending on if the PP is on the left or on the right, respectively. The perspective prediction may be based (e.g., be assumed to be based) on the first reference line (e.g., the closest reference arrays on top and the left of a target block). FIG. 11 illustrates example prediction with perspective points. The prediction may be based (e.g., always based) on the left and top reference arrays, for example, irrespective of the location of the PPs.

[0153] There may be more than two PPs, for example, for a (e.g., any) given prediction direction. As shown in FIG. 12, the PPs may be at different distances from the target block side. As shown in FIG. 12, two PPs may be at distances d and 2d from the top edge of the block, and their respective mirror PPs may be below the block. The PPs may be at distances d1 and d2 from the block (e.g., in general). For the predictionmode m, the PPs may be denoted as P(m,i ), P(m,2), etc., for example, in increasing order of their distance from a target block. FIG. 12 illustrates example perspective points at different distances from the target block but associated with the same prediction mode.

[0154] Dead zones for PPs may be present, determined, and / or detected.

[0155] There may be areas (e.g., some areas) where PPs may be refrained from being placed (e.g., should not be placed), for example, because the reference samples for prediction on the top and the left of a target block may be of finite length. As shown in FIG. 13, a PP placed in area dead zone for PPs may result in making the reference samples inadequate for prediction of the target block (e.g., full target block). These areas may be termed as dead zone for PPs. These dead zones may occur for mirror perspective points (e.g., mirror perspective points only). Perspective points lying in the dead zone may be refrained from being considered (e.g., not be considered) for prediction.

[0156] FIG. 13 illustrates an example dead zone for perspective points. The marked region (e.g., in FIG. 13) on the right side of the block may be a dead zone for horizontal perspective points. The marked region (e.g., in FIG. 13) at the bottom of the block may be a dead zone for vertical perspective points.

[0157]

[0158] Having defined a perspective point and a perspective mode, details of prediction with perspective may be described herein. The primary difference between the normal prediction and the prediction with perspective may include that the prediction direction along a row or a column may be variable in prediction with perspective. The angle parameter pred IntraAngle may be a function of the location of a target pixel. To distinguish between the two prediction types, we the term perspectiveAngle may refer to the original pred IntraAngle, and pred IntraAngleArray(x.y) may refer to the angle parameter at the pixel position (x,y).

[0159] FIG. 14 illustrates an example of derivation of the angle parameter for the target pixel at position (x,y). For illustration sake, FIG. 14 illustrates a vertical perspective mode. The case may be analogous for a horizontal perspective mode, for example, if the target block is transposed along with the reference arrays on the top and the left swapped. The width and heigh of the target block may be denoted as W and H respectively. The perspective height may be d, for example, which may be the vertical distance of the PP from the top edge of the target block. To avoid division operations, d may be assumed to be a power of 2. For example, d=k*H may be used, where k= 2n, n=0,1 ,... ,Kmax, where Kmax may be a preset integer. For a horizontal mode, d=k*W may be used, where k= 2n, n=0,1 ,...,Kmax. For the sake of derivation, (1 / 32) pixel resolution of prediction angles may be used, but the same may be obtained for (1 / 64) pixel resolution. A(x,y) may denote the predlntraAngleArray(x.y) value and Ao may denote the perspectiveAngle parameter, for example, which may be the same as the angle parameter associated with the prediction direction.

[0160] FIG. 15 illustrates an example of intra prediction with perspective. The predictor for a target pixel may be the reference sample lying in the direction joining the target pixel with the perspective point.

[0161] the angle parameter for the target pixel at (x,0) may be computed, for example, using Eq. 1. As shown in Eq. 1 , triangle similarity may be used.Hence, Eq. 2 may be determined.

[0162] As d may be a power of 2, the division operation in Eq. 2 may be implemented using a bit-shift.The pixel at (x,y) may be calculated using Eqs. 3 and 4.which may be equivalently expressed as Eq. 5.A(x,y) = A(x, 0) * (d / (d + y)) Eq. 5

[0163] To avoid division operation, the above calculation (e.g., Eq. 5) may be implemented as the following:A(%, y) = (A(%, 0) * S(d, y) + 128) » 8 Eq. 6 where,

[0164] The integer values S(d,y) may be precomputed and stored in an array.

[0165] Once the pred IntraAngleArray(x.y) has been computed, the steps (e.g., remaining steps) to identify the predictor sample may be the same steps as used in legacy procedures. For example, deltaPos(x.y) may denote the x-offset of the predictor from the target pixel at (x,y). For example, deltalnt(x.y) and deltaFrac(x.y) may denote the integral and fractional part of deltaPos(x.y). Referring to FIG. 15, Eqs. 8-10 may be determined: deltaPos x, y) = (1 + y) * A(x, y) Eq. 8 deltalnt x, y) = deltaPos x, y) » 5 Eq. 9 deltaFrac x, y) = deltaPos(x, y) & 31. Eq. 10For example, (1 / 32) pixel resolution may be used for the intra prediction angle. In the case of (1 / 64) pixel resolution for intra prediction angle, the integral and fractional parts of the offset may be obtained according to Eqs. 11-12: deltalnt x, y) = deltaPos x, y) » 6 Eq. 11 deltaFrac x, y) = deltaPos(x, y) & 63. Eq. 12

[0166] FIG. 16 illustrates an example of intra prediction with perspective. As shown in FIG. 16, the predictor for a target pixel may be interpolated with 6 nearest reference samples. Alternatively, it may be interpolated with 4 nearest reference samples or linearly interpolated using (e.g., only) the two nearest reference samples.

[0167] The predictor sample may be interpolated using the six nearest reference samples. Referring to FIG. 16, the six reference samples may be identified in accordance with Table 1.Table 1For example, refMain may be the main reference array pointing to the top-left corner pixel. The interpolation filter may be determined from the value of deltaFrac(x,y). If f(n) denotes the filter coefficients, the predictor sample is interpolated according to Eq. 13.P(x,y) = (f(O) *PO + f(l ) *P1 + f(2)*P2 + f(3) *P3 + f(4) *P4 + f(5) *P5 + 128) » 8 Eq . 13

[0168] In examples, deltaFrac may be used (e.g., only deltaFrac may be used) to determine the filter (e.g., which may remain constant for a given row of pixels). The filter may change from pixel to pixel, for example, even on the same row depending on the value of deltaFrac(x,y). The filter for a given target block may be either a smoothing filter or a cubic filter, for example, depending on an indication (e.g., a flag called interpolationFlag). The same criterion may be maintained here.

[0169] In examples, the four nearest reference samples (e.g., P1 , P2, P3, and P4) may be utilized for interpolating the predictor sample. Alternatively, the predictor may be linearly interpolated using the two nearest samples (e.g., only the two nearest reference samples) P2 and P3.

[0170] Design examples for inclusion of perspective prediction are provided herein. In the case of perspective prediction, one or more of the following may be assumed: there are no intra sub-partitions (ISP); the prediction is made using the first reference array; the DIMD indication (e.g., flag), the SGPM indication (e.g., flag), the TIMD indication (e.g., flag), the intraTmp (e.g., flag), etc., are disabled (e.g., all disabled); etc. The derivation of the most probable list (MPM) may remain unchanged.

[0171] In examples, a device (e.g., a video encoder) may check the angular prediction modes in both normal mode and in perspective mode. Associated with each angular mode, there may be a (e.g., only one) perspective point, and thus may be a (e.g., one) perspective prediction. The perspective point may be localized at a predefined distance from the target block position. A two-pass process (e.g., where initially a fast pass short-lists a few modes based on a partial RD criterion) may be performed, for example, to avoid exhaustive checks of all modes for full RD performance. The modes included in the short-list may undergothe RD check (e.g., full RD) check in the second pass. The mode that results in the minimum RD cost may be selected by the device (e.g., encoder) for the prediction. The device (e.g., encoder) may check the modes in the fast pass, for example, both in normal and perspective mode. An indication (e.g., a flag called perspectiveFlag) may be enabled, for example, if a candidate angular mode gives a lower cost with perspective mode (e.g., else it may be disabled). The device (e.g., encoder) may short-list a number of candidate modes to undergo a full RD check in the second pass. The device (e.g., encoder) may check the perspective indication (e.g., perspectiveFlag) value to decide which prediction mode to use for an angular mode, for example, for full RD cost calculation. The RD cost calculation may include the CABAC encoding of the perspective indication (e.g., perspectiveFlag). The device (e.g., encoder) may encode the prediction mode in the normal manner. If the best prediction mode is angular, it may encode (e.g., also encode) the perspective indication (e.g., perspectiveFlag). The device (e.g., a decoder) may decode the prediction mode in the normal manner. If the decoded prediction mode is angular, it may decode the perspective indication (e.g., perspectiveFlag). Depending on if the perspective indication (e.g., perspectiveFlag) is enabled or disabled, it may perform prediction of the target block with or without perspective.

[0172] In examples, the device (e.g., encoder) may limit the perspective prediction to the angular modes (e.g., only to the angular modes) included in the most probable modes (MPM) list. For each angular mode in the MPM list, the device (e.g., encoder) may check the performance in a fast pass and may add the candidate mode to the short-list of modes to be tested for full RD, for example, if the cost is lower than any of those already included in the list. The full RD check may be performed in the same manner as described herein. If the best mode is angular and belongs to the MPM list, the device (e.g., encoder) may encodes the perspective indication (e.g., perspectiveFlag). Accordingly, the device (e.g., decoder) may decode the perspectiveFlag, for example, if (e.g., only if) the mode is angular and belongs to the MPM list.

[0173] In examples, the device (e.g., encoder) may check a best angular mode (e.g., only the best angular mode) in the short-list with perspective prediction before the full RD check. The mode with perspective prediction may replace that mode, for example, if the cost is lower than that of the (e.g., any of the) modes in the short-list with normal prediction. The full RD check may be performed as described herein. The device (e.g., encoder) may encode the perspective indication (e.g., perspectiveFlag), for example, if the best mode is angular. The device (e.g., decoder) may decode the perspective indication (e.g., perspectiveFlag), for example, if the decoded mode is angular.

[0174] In examples, multiple perspective points may be used with a (e.g., each) angular mode. The device (e.g., encoder) may check the angular prediction modes, for example, in both normal mode and in multiple perspective modes. The design may be similar to those described herein except that there are multiple perspective points. Besides the perspective indication (e.g., perspectiveFlag), there may be another syntaxelement associated with a perspective mode indication (e.g., called perspectiveModeFlag) to distinguish a (e.g., one) perspective mode from another. The perspective mode indication (e.g., perspectiveModeFlag) may be encoded, for example, if the perspective indication (e.g., perspectiveFlag) is enabled. The perspective mode indication (e.g., perspectiveModeFlag) may be encoded with one bit, for example, if there are multiple (e.g., two) perspective points (e.g., a pair of points consisting of a perspective point and its mirror). If there are three perspective points, the perspectiveModeFlag can be encoded with two bits (e.g., 0, 10, or 11). The device (e.g., decoder) may decode the perspective indication (e.g., perspectiveFlag), for example, if the mode is angular. The perspectiveModeFlag may be decoded, for example, if the perspectiveFlag is 1. The perspective point may be selected and the prediction may be performed accordingly, for example, depending on the decoded value.

[0175] In examples, the device (e.g., encoder) may limit the perspective prediction to angular modes (e.g., only to the angular modes), for example, included in the MPM list. This may be similar to the processes described here, but with multiple perspective points associated with an angular MPM mode.

[0176] In examples,, one or more fixed PPs may be used. For example, the device (e.g., encoder) may have (e.g., decide to have) a (e.g., only one) vertical perspective and a (e.g., one) horizontal perspective. The perspective prediction using these PPs may be considered as different (e.g., new) prediction modes, for example, on top of the existing modes. The encoding of the prediction mode may be done in different ways. One way may be to use a perspective indication (e.g., perspectiveFlag) (e.g., as described herein). The perspective indication (e.g., perspectiveFlag) may be decoded, for example, if the decoded prediction mode is associated with one of the PPs (e.g., else not). The perspective modes may be included in the list of modes to be encoded. The perspective modes may be included in the MPM list, for example, if the corresponding angular modes are (e.g., already) in MPM list. In this case, the existing encoding and decoding of modes may remain similar, for example, except that the number of modes may be increased. A perspective indication (e.g., perspectiveFlag) may be used along with a list of perspectiveModes. The perspective indication (e.g., perspectiveFlag) may indicate if perspective prediction is used. The index of the perspective mode in the list containing the (e.g., all the) perspective modes may be encoded. In this case, the device (e.g., decoder) may decode the perspective indication (e.g., perspectiveFlag) first. If the flag is 1 , it may decode the candidate perspective mode; else it may decode the normal mode in the usual manner (e.g., as described herein).

[0177] In examples, a fixed PP may be decided based on the MPM list modes, or the DIMD mode or the TIMD modes, etc. Among predefined PPs, the PP closest to the MPM modes, or the DIMD mode, or the TIMD modes, etc., may be chosen for perspective prediction. In this case the (e.g., only the) perspective indication (e.g., perspectiveFlag) may be encoded (e.g., needs to be encoded) as the location of the PP maybe easily identified. It may be decided to use a perspective mode indication (e.g., perspectiveModeFlag), for example, if there are multiple PPs along the same direction.

[0178] Perspective points may be defined with respect to the center of a target block. In examples, PPs may be defined with respect to another point, for example, which may be at some predefined offset (Ix.ly) from the center of a target block. Perspective points may be defined with the prediction directions associated with specified intra prediction modes. In examples, PPs may be defined at a predefined angular offset from the prediction directions associated with specified prediction modes.

[0179] An intra prediction model based on perspective may be provided, enabled, and / or used. In sequences having perspectives, this prediction model may enable (e.g., result in) higher compression efficiency (e.g., as compared with a normal prediction model that does not use any perspective model).

[0180] Although features and elements are described above in particular combinations, one of ordinary skill in the art will appreciate that each feature or element can be used alone or in any combination with the other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, 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 versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

CLAIMS1. A video decoding device, comprising: a processor configured to: determine that a perspective mode is used for a coding block; determine a perspective point associated with the coding block, wherein the perspective point is associated with a prediction direction and a distance from the coding block; and decode the coding block based on the determined perspective point.

2. The video decoding device of claim 1 , wherein the processor is further configured to: obtain an indication associated with using perspective mode; determine that an angular prediction mode is used for the coding block; based on the determination that the angular prediction mode is used for the coding block, decode the indication associated with using perspective mode, wherein the determination that the perspective mode is used for the coding block is based on the decoded indication.

3. The video decoding device of claim 1 or 2, wherein the perspective point is a point associated with an intersection of a prediction direction at a center of the coding block and associated with a line parallel to a side of the coding block at an offset distance.

4. The video decoding device of any of claims 1 to 3, wherein the processor is further configured to: obtain an indication that indicates a most probably modes (MPM) list, wherein candidate intra prediction modes are determined based at least on the MPM list.

5. The video decoding device of any of claims 1 to 4, wherein the perspective mode is a first perspective mode, wherein the perspective point is a first perspective point, and wherein the processor is further configured to: determine whether a second perspective mode is used for the coding block; and based on a determination that the second perspective mode is used for the coding block, determine a second perspective point associated with the coding block, wherein the coding block is decoded based on the first perspective point and the second perspective point.

6. The video decoding device of claim 5, wherein the processor is further configured to: obtain a perspective mode indication, wherein the perspective mode indication indicates the first perspective mode and the second perspective mode.

7. The video decoding device of any of claims 1 to 6, wherein perspective point is a fixed perspective point.

8. The video decoding device of any of claims 1 to 7, wherein the perspective point is determined based on at least one of a most probably modes (MPM) list, a decoder-side intra mode derivation mode, or a template-based intra mode derivation (TIMD) mode.

9. The video decoding device of any of claims 1 to 8, wherein the processor is further configured to: determine that an angular intra prediction mode is used for a coding block, wherein the determination of whether to use a perspective mode for the coding block is based on the determination that an angular intra prediction mode is used for the coding block.

10. The video decoding device of any of claims 1 to 9, wherein the processor is further configured to: determine an angle parameter associated with the perspective point, wherein the angle parameter is determined based on a height associated with the coding block, a width associated with the coding block, and a perspective height associated with the perspective point.11 . The video decoding device of claim 10, wherein the height associated with the perspective point is a vertical distance between the perspective point and a top edge of the coding block.

12. A video encoding device, comprising: a processor configured to: determine that a perspective mode is used for a coding block; determine a perspective point associated with the coding block, wherein the perspective point is associated with a prediction direction and a distance from the coding block; and encode the coding block based on the determined perspective point.

13. The video encoding device of claim 12, wherein the perspective point is a point associated with an intersection of a prediction direction at a center of the coding block and associated with a line parallel to a side of the coding block at an offset distance.

14. The video encoding device of claim 12 or 13, wherein the determination that the perspective mode is used for the coding block comprises a rate distortion (RD) cost determination associated with candidate intra prediction modes and a determination that the perspective mode is associated with a lowest RD cost among the candidate intra prediction modes.

15. The video encoding device of any of claims 12 to 14, wherein for the determination that the perspective mode is used for the coding block, the processor is further configured to: determine a shortlist of candidate intra prediction modes from a set of candidate intra prediction modes based on a partial rate distortion (RD) criterion; and determine that the perspective mode is associated with a lowest RD cost among the shortlist of candidate intra prediction modes.

16. The video encoding device of claim 15, wherein the determination that the perspective mode is associated with the lowest RD cost among the shortlist of candidate intra prediction modes is associated with a full RD check.

17. The video encoding device of claim 15 or 16, wherein the processor is further configured to: obtain an indication that indicates a most probably modes (MPM) list, wherein the candidate intra prediction modes are determined based at least on the MPM list.

18. The video encoding device of any of claims 12 to 17, wherein the perspective mode is a first perspective mode, wherein the perspective point is a first perspective point, and wherein the processor is further configured to: determine whether a second perspective mode is used for the coding block; based on a determination that the second perspective mode is used for the coding block, determine a second perspective point associated with the coding block, wherein the coding block is encoded based on the first perspective point and the second perspective point; and include in video data the encoded coding block and an indication that indicates the first perspective mode and the second perspective mode.

19. The video encoding device of any of claims 12 to 18, wherein the perspective point is a fixed perspective point.

20. The video encoding device of any of claims 12 to 19, wherein the perspective point is determined based on one of a most probable modes (MPM) list, a decoder-side intra mode derivation mode, or a template-based intra mode derivation (TIMD) mode.

21. The video encoding device of any of claims 12 to 20, wherein the processor is further configured to: determine that an angular intra prediction mode is used for a coding block, wherein the determination of whether to use a perspective mode for the coding block is based on the determination that an angular intra prediction mode is used for the coding block.

22. The video encoding device of any of claims 12 to 21 , wherein the processor is further configured to: include in video data the encoded coding block and an indication that indicates to use the perspective mode for the encoded coding block.

23. The video encoding device of any of claims 12 to 22, wherein the processor is further configured to: determine an angle parameter associated with the perspective point, wherein the angle parameter is determined based on a height associated with the coding block, a width associated with the coding block, and a perspective height associated with the perspective point.

24. The video encoding device of claim 23, wherein the height associated with the perspective point is a vertical distance between the perspective point and a top edge of the coding block.

25. A method for video decoding, comprising: determining that a perspective mode is used for a coding block; determining a perspective point associated with the coding block, wherein the perspective point is associated with a prediction direction and a distance from the coding block; and decoding the coding block based on the determined perspective point.

26. The method of claim 25, the method further comprising: obtaining an indication associated with using perspective mode; determining that an angular prediction mode is used for the coding block;based on the determination that the angular prediction mode is used for the coding block, decoding the indication associated with using perspective mode, wherein the determination that the perspective mode is used for the coding block is based on the decoded indication.

27. The method of claim 25 or 26, wherein the perspective point is a point associated with an intersection of a prediction direction at a center of the coding block and associated with a line parallel to a side of the coding block at an offset distance.

28. The method of any of claims 25 to 27, wherein the processor is further configured to: obtain an indication that indicates a most probably modes (MPM) list, wherein candidate intra prediction modes are determined based at least on the MPM list.

29. The method of any of claims 25 to 28, wherein the perspective mode is a first perspective mode, wherein the perspective point is a first perspective point, and wherein the method further comprises: determining whether a second perspective mode is used for the coding block; and based on a determination that the second perspective mode is used for the coding block, determining a second perspective point associated with the coding block, wherein the coding block is decoded based on the first perspective point and the second perspective point.

30. The method of claim 29, wherein the method further comprises: obtaining a perspective mode indication, wherein the perspective mode indication indicates the first perspective mode and the second perspective mode.31 . The method of any of claims 25 to 30, wherein perspective point is a fixed perspective point.

32. The method of any of claims 25 to 31 , wherein the perspective point is determined based on at least one of a most probably modes (MPM) list, a decoder-side intra mode derivation mode, or a templatebased intra mode derivation (TIMD) mode.

33. The method of any of claims 25 to 32, wherein the method further comprises: determining that an angular intra prediction mode is used for a coding block, wherein the determination of whether to use a perspective mode for the coding block is based on the determination that an angular intra prediction mode is used for the coding block.

34. The method of any of claims 25 to 33, wherein the method further comprises: determining an angle parameter associated with the perspective point, wherein the angle parameter is determined based on a height associated with the coding block, a width associated with the coding block, and a perspective height associated with the perspective point.

35. The method of claim 34, wherein the height associated with the perspective point is a vertical distance between the perspective point and a top edge of the coding block.

36. A method for video encoding, the method comprising: determining that a perspective mode is used for a coding block; determining a perspective point associated with the coding block, wherein the perspective point is associated with a prediction direction and a distance from the coding block; and encoding the coding block based on the determined perspective point.

37. The method of claim 36, wherein the perspective point is a point associated with an intersection of a prediction direction at a center of the coding block and associated with a line parallel to a side of the coding block at an offset distance.

38. The method of claim 36 or 37, wherein the determination that the perspective mode is used for the coding block comprises a rate distortion (RD) cost determination associated with candidate intra prediction modes and a determination that the perspective mode is associated with a lowest RD cost among the candidate intra prediction modes.

39. The method of any of claims 36 to 38, wherein for the determination that the perspective mode is used for the coding block, the method further comprises: determining a shortlist of candidate intra prediction modes from a set of candidate intra prediction modes based on a partial rate distortion (RD) criterion; and determining that the perspective mode is associated with a lowest RD cost among the shortlist of candidate intra prediction modes.

40. The method of claim 39, wherein the determination that the perspective mode is associated with the lowest RD cost among the shortlist of candidate intra prediction modes is associated with a full RD check.41 . The method of claim 39 or 40, wherein the method further comprises: obtaining an indication that indicates a most probably modes (MPM) list, wherein the candidate intra prediction modes are determined based at least on the MPM list.

42. The method of any of claims 36 to 41 , wherein the perspective mode is a first perspective mode, wherein the perspective point is a first perspective point, and wherein the method further comprises: determining whether a second perspective mode is used for the coding block; based on a determination that the second perspective mode is used for the coding block, determining a second perspective point associated with the coding block, wherein the coding block is encoded based on the first perspective point and the second perspective point; and including in video data the encoded coding block and an indication that indicates the first perspective mode and the second perspective mode.

43. The method of any of claims 36 to 42, wherein the perspective point is a fixed perspective point.

44. The method of any of claims 36 to 43, wherein the perspective point is determined based on one of a most probable modes (MPM) list, a decoder-side intra mode derivation mode, or a template-based intra mode derivation (TIMD) mode.

45. The method of any of claims 36 to 44, wherein the method further comprises: determining that an angular intra prediction mode is used for a coding block, wherein the determination of whether to use a perspective mode for the coding block is based on the determination that an angular intra prediction mode is used for the coding block.

46. The method of any of claims 36 to 45, wherein the method further comprises: including in video data the encoded coding block and an indication that indicates to use the perspective mode for the encoded coding block.

47. The method of any of claims 36 to 46, wherein method further comprises: determining an angle parameter associated with the perspective point, wherein the angle parameter is determined based on a height associated with the coding block, a width associated with the coding block, and a perspective height associated with the perspective point.

48. The method of claim 47, wherein the height associated with the perspective point is a vertical distance between the perspective point and a top edge of the coding block.

Images