Block partitioning associated with video compression

Abstract

Described herein are systems, methods, and instrumentalities associated with video coding (e.g., encoding and / or decoding). According to embodiments of the present disclosure, a video decoding device or a video encoding device may be configured to determine that a parent coding unit (CU) is to be partitioned into four or more sub-coding units (sub-CUs), and determine whether to perform the partition based on a center of the parent CU. If the determination is not to perform the partition based on the center of the parent CU, the video decoding device or the video encoding device may split the parent CU into the four or more sub-CUs along at least a first vertical split line and a first horizontal split line such that an intersection of the first vertical split line and the first horizontal split line may be shifted away from the center of the parent CU.

Description

BLOCK PARTITIONING ASSOCIATED WITH VIDEO COMPRESSIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of European Patent Application No. 23306679.4, filed Oct. 2, 2023, the disclosure of which is incorporated herein by reference in its entirety.BAKGROUND

[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] Described herein are systems, methods, and instrumentalities associated with video coding (e.g., encoding and / or decoding). According to embodiments of the present disclosure, a video decoding device may be configured to determine that a parent coding unit (CU) is to be partitioned into four or more sub-coding units (sub-CUs), and determine whether to perform the partition based on a center of the parent CU. If the determination is not to perform the partition based on the center of the parent CU, the video decoding device may split the parent CU into the four or more sub-CUs along at least a first vertical split line and a first horizontal split line such that an intersection of the first vertical split line and the first horizontal split line may be shifted away from the center of the parent CU.

[0004] In examples, the intersection of the first vertical split line and the first horizontal split line may be located to the above-right of the center of the parent CU, the above-left of the center of the parent CU, the below-right of the center of the parent CU, or the below-left of the center of the parent CU. In examples, the determination of whether to perform the partition based on the center of the parent CU may be made based on an indication received from a bitstream. In examples, the indication received from the bitstream may indicate a position of the intersection of the first vertical split line and the first horizontal split line relative to the center of the parent CU. In examples, the indication received from the bitstream may indicate a split ratio in at least one of a vertical direction or a horizontal direction.

[0005] In examples, the video decoding device being configured to split the sub-CU along the second vertical split line and the second horizontal split line may comprise the video decoding device being configured to determine a split ratio in at least one of a vertical direction or a horizontal direction split ratio based on a size of the parent CU, a number of luma samples in the parent CU, or a depth level of a coding tree associated with of the parent CU.

[0006] In examples, the video decoding device may be further configured to determine whether to partition a sub-CU of the four or more sub-CUs based on a center of the sub-CU. If the determination is not to partition the sub-CU based on the center of the sub-CU, the video decoding device may split the sub-CU along at least a second vertical split line and a second horizontal split line such that an intersection of the second vertical split line and the second horizontal split line is shifted away from the center of the sub-CU. In examples, the sub-CU may have a height or a width that is not a power of 2, and a CU obtained from splitting the sub-CU along the second vertical split line and the second horizontal split line may have a height or a width that is a power of 2.

[0007] According to embodiments of the present disclosure, a video encoding device may be configured to determine that a parent coding unit (CU) is to be partitioned into four or more sub-coding units (sub-CUs), and determine whether to perform the partition based on a center of the parent CU. If the determination is not to perform the partition based on the center of the parent CU, the video encoding device may split the parent CU into the four or more sub-CUs along at least a first vertical split line and a first horizontal split line such that an intersection of the first vertical split line and the first horizontal split line is shifted away from the center of the parent CU.

[0008] In examples, the intersection of the first vertical split line and the first horizontal split line may be located to the above-right of the center of the parent CU, the above-left of the center of the parent CU, the below-right of the center of the parent CU, or the below-left of the center of the parent CU. In examples, the determination of whether to perform the partition based on the center of the parent CU may be made based on an indication received from a bitstream, and wherein the indication indicates a split ratio in at least one of a vertical direction or a horizontal direction.

[0009] A computer program product may be stored on a non-transitory computer readable medium and may comprise program code instructions for implementing (e.g., when the instructions are executed by a processor) the steps of a method performed by the video decoding device or the video encoding device.

[0010] Video data may comprise information representative of a coding unit encoded by the video encoding device described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented.

[0012] 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.

[0013] FIG. 1 C 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.

[0014] 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. 1A according to an embodiment.

[0015] FIG. 2 is a diagram illustrating an example video encoder.

[0016] FIG. 3 is a diagram illustrating an example video decoder.

[0017] FIG. 4 is a diagram illustrating an example of a system in which various aspects and examples may be implemented.

[0018] FIG. 5 is a diagram illustrating an example of a coding tree.

[0019] FIG. 6 is a diagram illustrating an example of a division of a coding tree unit.

[0020] FIG. 7 is a diagram illustrating an example of partitioning of coding units.

[0021] FIG. 8 is a diagram illustrating an example of a quad-tree plus binary-tree (QTBT) CTU.

[0022] FIG. 9 is a diagram illustrating examples of triple tree coding unit splitting modes.

[0023] FIG. 10 is a diagram illustrating examples of coding unit splitting modes.

[0024] FIG. 11 is a diagram illustrating examples of CU binary asymmetric splitting modes.

[0025] FIG. 12 is a diagram illustrating examples of extended set of CU split modes.

[0026] FIG. 13 is a diagram illustrating examples of coding structures to encode a picture.

[0027] FIG. 14 is a diagram illustrating an example of signaling associated with block partitioning.

[0028] FIG. 15 is a diagram illustrating an example of a shifted quad-tree split mode.

[0029] FIG. 16 is a diagram illustrating an example of a block partitioning syntax arrangement.

[0030] FIG. 17 is a diagram illustrating an example of a block division process.

[0031] FIG. 18 is a diagram illustrating examples of recursive splitting of blocks.

[0032] FIG. 19 is a diagram illustrating an example of signaling associated with block partitioning.

[0033] FIG. 20 is a diagram illustrating an example of signaling associated with block partitioning.

[0034] FIG. 21 is a diagram illustrating an example of recursive quad-tree splitting.

[0035] FIG. 22 is a diagram illustrating an example of recursive shifted quad-tree splitting.

[0036] FIG. 23 is a diagram illustrating examples of shifted non-square quad-tree split modes.

[0037] FIG. 24 is a diagram illustrating examples of shifted quad-tree split modes.

[0038] FIG. 25 is a diagram illustrating an example of a process of transforming a shifted quadtree split.

[0039] FIG. 26 is a diagram illustrating an example of a process of transforming a shifted quadtree split.DETAILED DESCRIPTION

[0040] A more detailed understanding can be had from the following description, given by way of example in conjunction with the accompanying drawings.

[0041] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments can be implemented. The communications system 100 can be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 can enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 can 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.

[0042] As shown in FIG. 1A, the communications system 100 can 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. Each of the WTRUs 102a, 102b, 102c, 102d can 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 can be referred to as a “station” and / or a “STA”, can be configured to transmit and / or receive wireless signals and can 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-Fi 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 industrialwireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d can be interchangeably referred to as a UE.

[0043] The communications systems 100 can also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b can 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 can 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 can include any number of interconnected base stations and / or network elements.

[0044] The base station 114a can be part of the RAN 104 / 113, which can 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 can be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which can be referred to as a cell (not shown). These frequencies can be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell can provide coverage for a wireless service to a specific geographical area that can be relatively fixed or that can change over time. The cell can further be divided into cell sectors. For example, the cell associated with the base station 114a can be divided into three sectors. Thus, in one embodiment, the base station 114a can include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a can employ multiple-input multiple output (MIMO) technology and can utilize multiple transceivers for each sector of the cell. For example, beamforming can be used to transmit and / or receive signals in desired spatial directions.

[0045] The base stations 114a, 114b can communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which can be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 can be established using any suitable radio access technology (RAT).

[0046] More specifically, as noted above, the communications system 100 can be a multiple access system and can 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 / 1 13 and the WTRUs 102a, 102b, 102c can implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which can establish the air interface 115 / 116 / 117 usingwideband CDMA (WCDMA). WCDMA can include communication protocols such as High-Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA can include High-Speed Downlink (DL) Packet Access (HSDPA) and / or High-Speed UL Packet Access (HSUPA).

[0047] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which can establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0048] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement a radio technology such as NR Radio Access, which can establish the air interface 116 using New Radio (NR).

[0049] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c can 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 can be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., an eNB and a gNB).

[0050] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c can 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.

[0051] The base station 114b in FIG. 1 A can be a wireless router, Home Node B, Home eNode B, or access point, for example, and can 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 can 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 can 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 can 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 can have a direct connection to theInternet 110. Thus, the base station 114b can not be required to access the Internet 110 via the CN 106 / 115.

[0052] The RAN 104 / 113 can be in communication with the CN 106 / 115, which can 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 can 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 can 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 can 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 can be utilizing a NR radio technology, the CN 106 / 115 can also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0053] The CN 106 / 115 can 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 can include circuit- switched telephone networks that provide plain old telephone service (POTS). The Internet 110 can 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 can include wired and / or wireless communications networks owned and / or operated by other service providers. For example, the networks 112 can include another CN connected to one or more RANs, which can employ the same RAT as the RAN 104 / 113 or a different RAT.

[0054] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 can include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d can include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A can be configured to communicate with the base station 114a, which can employ a cellular-based radio technology, and with the base station 114b, which can employ an IEEE 802 radio technology.

[0055] FIG. 1 B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1 B, the WTRU 102 can include a processor 118, a transceiver 120, a transmit / receive element 122, aspeaker / 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 can include any subcombination of the foregoing elements while remaining consistent with an embodiment.

[0056] The processor 118 can 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 can 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 can be coupled to the transceiver 120, which can 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 can be integrated together in an electronic package or chip.

[0057] The transmit / receive element 122 can 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 can be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 can 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 can be configured to transmit and / or receive both RF and light signals. It will be appreciated that the transmit / receive element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0058] Although the transmit / receive element 122 is depicted in FIG. 1 B as a single element, the WTRU 102 can include any number of transmit / receive elements 122. More specifically, the WTRU 102 can employ MIMO technology. Thus, in one embodiment, the WTRU 102 can include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0059] The transceiver 120 can 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 can have multi-mode capabilities. Thus, the transceiver 120 can include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11 , for example.

[0060] The processor 118 of the WTRU 102 can be coupled to, and can 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 can also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 can 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 nonremovable memory 130 can include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 can 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 can 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).

[0061] The processor 118 can receive power from the power source 134, and can be configured to distribute and / or control the power to the other components in the WTRU 102. The power source 134 can be any suitable device for powering the WTRU 102. For example, the power source 134 can 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.

[0062] The processor 118 can also be coupled to the GPS chipset 136, which can 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 can 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 can acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment.

[0063] The processor 118 can further be coupled to other peripherals 138, which can 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 can 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 can include one or more sensors, the sensors can be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, atemperature 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.

[0064] The WTRU 102 can 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) can be concurrent and / or simultaneous. The full duplex radio can 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 WTRU 102 can 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)).

[0065] FIG. 1 C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 can employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 can also be in communication with the CN 106.

[0066] The RAN 104 can include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 can include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c can 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 can implement MIMO technology. Thus, the eNode-B 160a, for example, can use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a.

[0067] Each of the eNode-Bs 160a, 160b, 160c can be associated with a particular cell (not shown) and can 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 can communicate with one another over an X2 interface.

[0068] The CN 106 shown in FIG. 1 C can 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 can be owned and / or operated by an entity other than the CN operator.

[0069] The MME 162 can be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and can serve as a control node. For example, the MME 162 can 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 MME162 can 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.

[0070] The SGW 164 can be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The SGW 164 can generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 can perform other functions, such as anchoring user planes during inter-eNode B 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.

[0071] The SGW 164 can be connected to the PGW 166, which can 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.

[0072] The CN 106 can facilitate communications with other networks. For example, the CN 106 can 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 can include, or can 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 can provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which can include other wired and / or wireless networks that are owned and / or operated by other service providers.

[0073] Although the WTRU is described in FIGS. 1 A-1 D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal can use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0074] In representative embodiments, the other network 112 can be a WLAN.

[0075] A WLAN in Infrastructure Basic Service Set (BSS) mode can have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP can 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 can arrive through the AP and can be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS can be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS can be sent through the AP, for example, where the source STA can send traffic to the AP and the AP can deliver the traffic to the destination STA. The traffic between STAs within a BSS can be considered and / or referred to as peer-to-peer traffic. The peer-to-peer traffic can be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments,the DLS can use an 802.11e DLS or an 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode cannot have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS can communicate directly with each other. The IBSS mode of communication can sometimes be referred to herein as an “ad-hoc” mode of communication.

[0076] When using the 802.11ac infrastructure mode of operation or a similar mode of operations, the AP can transmit a beacon on a fixed channel, such as a primary channel. The primary channel can be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel can be the operating channel of the BSS and can be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) can be implemented, for example in in 802.11 systems. For CSMA / CA, the STAs (e.g., every STA), including the AP, can sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA can back off. One STA (e.g., only one station) can transmit at any given time in a given BSS.

[0077] High Throughput (HT) STAs can 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.

[0078] Very High Throughput (VHT) STAs can support 20MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. The 40 MHz, and / or 80 MHz, channels can be formed by combining contiguous 20 MHz channels. A 160 MHz channel can be formed by combining 8 contiguous 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which can be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, can be passed through a segment parser that can divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, can be done on each stream separately. The streams can be mapped on to the two 80 MHz channels, and the data can be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration can be reversed, and the combined data can be sent to the Medium Access Control (MAC).

[0079] 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 802.1 1af and 802.11ah relative to those used in 802.11 n, and 802.11 ac. 802.11 af 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 can support Meter Type Control / Machine-Type Communications, such as MTC devices in a macro coverage area. MTCdevices can have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and / or limited bandwidths. The MTC devices can include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0080] WLAN systems, which can 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 can be designated as the primary channel. The primary channel can have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can 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 can 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 can 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 can be considered busy even though a majority of the frequency bands remains idle and can be available.

[0081] In the United States, the available frequency bands, which can 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.

[0082] 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 can employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 can also be in communication with the CN 115.

[0083] The RAN 113 can include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 can include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c can 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 can implement MIMO technology. For example, gNBs 180a, 108b can utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a, for example, can 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 can implement carrier aggregation technology. For example, the gNB 180a can transmit multiple component carriers to the WTRU 102a (not shown). A subset of these componentcarriers can be on unlicensed spectrum while the remaining component carriers can be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c can implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a can receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0084] The WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing can vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c can 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).

[0085] The gNBs 180a, 180b, 180c can 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 can 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 can utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c can 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 can 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 can serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c can provide additional coverage and / or throughput for servicing WTRUs 102a, 102b, 102c.

[0086] Each of the gNBs 180a, 180b, 180c can be associated with a particular cell (not shown) and can 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 can communicate with one another over an Xn interface.

[0087] The CN 115 shown in FIG. 1 D can 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 beappreciated that any of these elements can be owned and / or operated by an entity other than the CN operator.

[0088] The AMF 182a, 182b can be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and ean serve as a control node. For example, the AMF 182a, 182b can 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 can 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 can be established for different use cases such as services relying on ultrareliable 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 can 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.

[0089] The SMF 183a, 183b can be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b can also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b can select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b can 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 can be IP-based, non-IP based, Ethernet-based, and the like.

[0090] The UPF 184a, 184b can be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which can 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 can 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.

[0091] The CN 115 can facilitate communications with other networks. For example, the CN 115 can include, or can 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 can provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which can include other wired and / orwireless networks that are owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c can 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.

[0092] In view of Figures 1 A-1 D, and the corresponding description of Figures 1 A-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, can be performed by one or more emulation devices (not shown). The emulation devices can be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices can be used to test other devices and / or to simulate network and / or WTRU functions.

[0093] The emulation devices can 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 can 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 can perform the one or more, or all, functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation device can be directly coupled to another device for purposes of testing and / or can performing testing using over-the-air wireless communications.

[0094] The one or more emulation devices can 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 can be utilized in a testing scenario in a testing laboratory and / or a nondeployed (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 can be test equipment. Direct RF coupling and / or wireless communications via RF circuitry (e.g., which can include one or more antennas) can be used by the emulation devices to transmit and / or receive data.

[0095] 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 can 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 can be combined and interchanged to provide further aspects. Moreover, the aspects can be combined and interchanged with aspects described in earlier filings as well.

[0096] The aspects described and contemplated in this application can be implemented in many different forms. The figures provided herein can provide some examples, but other examples are contemplated. The discussion of the figures 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 can be implemented as a method, an apparatus, a computer readable medium (e.g., storage medium) comprising (e.g., 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. When referred to herein, a bitstream can refer to transmitted data, but can also refer to data that is stored, generated, and / or accessed without being transmitted (e.g., non-transitory data).

[0097] In the present application, the terms “reconstructed” and “decoded” can be used interchangeably, the terms “pixel” and “sample” can be used interchangeably, the terms “image,” “picture” and “frame” can be used interchangeably.

[0098] 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 can be modified or combined. Additionally, terms such as “first”, “second”, etc. can 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 can occur, for example, before, during, or in an overlapping time period with the second decoding.

[0099] Various methods and other aspects described in this application can 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 can be applied, for example, to any type, format or version of video coding, whether described in a standard or a recommendation, whether preexisting or future-developed, and extensions of any such standards and recommendations. Unless indicated otherwise, or technically precluded, the aspects described in this application can be used individually or in combination.

[0100] Various numeric values are used in examples described in the present application. These and other specific values are for purposes of describing examples and the aspects described are not limited to these specific values.

[0101] 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.

[0102] Before being encoded, the video sequence can 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 can be associated with the pre-processing, and attached to the bitstream.

[0103] 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 i ntra / i nter 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.

[0104] 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.

[0105] 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).

[0106] 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.

[0107] In particular, the input of the decoder includes a video bitstream, which can be generated by video encoder 200. The bitstream is first entropy decoded 330 to obtain transform coefficients, motionvectors, and other coded information. The picture partition information indicates how the picture is partitioned. The decoder can 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 can 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.

[0108] 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) can be sent to a display device for rendering to a user.

[0109] FIG. 4 is a diagram showing an example of a system in which various aspects and examples described herein can be implemented. System 400 can 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, can 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.

[0110] 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-OnlyMemory (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.

[0111] 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 can 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 can be implemented as a separate element of system 400 or can be incorporated within processor 410 as a combination of hardware and software as known to those skilled in the art.

[0112] Program code to be loaded onto processor 410 or encoder / decoder 430 to perform the various aspects described in this document can 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.

[0113] 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 can be either the processor 410 or the encoder / decoder module 430) is used for one or more of these functions. The external memory can 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 one example, a fast external dynamic volatile memory such as a RAM is used as working memory for video encoding and decoding operations.

[0114] The input to the elements of system 400 can 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.

[0115] 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 can 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 can 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 near-baseband 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.

[0116] 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, can be implemented, for example, within a separate input processing IC or within processor 410 as necessary. Similarly, aspects of USB or HDMI interface processing can 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 with the memory and storage elements to process the datastream as necessary for presentation on an output device.

[0117] Various elements of system 400 can be provided within an integrated housing, Within the integrated housing, the various elements can 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.

[0118] 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 can be implemented, for example, within a wired and / or a wireless medium.

[0119] 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.

[0120] 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 can 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.

[0121] 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 Electronics Control (CEC), or other communications protocols that enable device-to-device control with or without user intervention. The output devices can be communicatively coupled to system 400 via dedicated connections through respective interfaces 470, 480, and 490. Alternatively, the output devices can be connected to system 400 using the communications channel 460 via the communications interface 450. The display 475 and speakers 485 can 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.

[0122] 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 can be provided via dedicated output connections, including, for example, HDMI ports, USB ports, or COMP outputs.

[0123] The examples can 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 can be implemented by one or more integrated circuits. The memory 420 can be of any type appropriate to the technical environment and can 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 can 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.

[0124] Various implementations include 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.

[0125] 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 acombination 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.

[0126] Various implementations include 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.

[0127] 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.

[0128] Note that syntax elements as used herein are descriptive terms. As such, they do not preclude the use of other syntax element names.

[0129] 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.

[0130] The implementations and aspects described herein can 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 can be implemented in, for example, appropriate hardware, software, and firmware. The methods can 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.

[0131] 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 forth described 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.

[0132] Additionally, this application can 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 can include receiving, retrieving, constructing, generating, and / or determining.

[0133] Further, this application can 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.

[0134] Additionally, this application can 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.

[0135] It is to be appreciated that the use of any of the following 7”, “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 can be extended, as is clear to one of ordinary skill in this and related arts, for as many items as are listed.

[0136] Also, as used herein, the word “signal” refers to, among other things, indicating something to a corresponding decoder. 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 same particular parameter. Conversely, if the decoder already has the particular parameter as well as others, then signaling can 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 can 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.

[0137] As will be evident to one of ordinary skill in the art, implementations can produce a variety of signals formatted to carry information that can 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 can be formatted to carry the bitstream of a described example. Such a signal can be formatted, for example, as an electromagnetic wave (for example, using a radio frequency portion of spectrum) or as a baseband signal. The formatting can include, for example, encoding a data stream and modulating a carrier with the encoded data stream. The information that the signal carries can be, for example, analog or digital information. The signal can be transmitted over a variety of different wired or wireless links, as is known. The signal can be stored on, or accessed or received from, a processor-readable medium.

[0138] Many examples are described herein. Features of examples can be provided alone or in any combination, across various claim categories and types. Further, examples can 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 can be implemented in a bitstream or signal that includes information generated as described herein. The information can 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 can be implemented by creating and / or transmitting and / or receiving and / or decoding a bitstream or signal. For example, features described herein can be implemented a method, process, apparatus, medium storing instructions (e.g., computer-readable medium), medium storing data, or signal. For example, features described herein can 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 can display (e.g., using a monitor, screen, or othertype 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 can receive a signal including an encoded image and perform decoding.

[0139] During video compression, a picture may be divided into Coding Tree Units (CTUs). The size of a CTU may be, for example, 64x64, 128x128, or 256x256 pixels. FIG. 5 illustrates an example of Coding Tree Unit and Coding Tree structure to represent a compressed picture (e.g., an encoded picture). A (e.g., each) CTU may be represented by a Coding Tree in the compressed domain. Quad-tree division of the CTU may have many associated leaf nodes, where a (e.g., each) leaf may be referred to as a Coding Unit (CU).

[0140] FIG. 6 illustrates an example of division of a Coding Tree Unit into Coding Units, Prediction Units, and Transform Units. A (e.g., each) CU may be given Intra and / or Inter prediction parameters (e.g., Prediction Info). A CU may be partitioned (e.g., spatially partitioned) into one or more Prediction Units (PUs). A (e.g., each) PU may be assigned prediction information. An Intra or Inter coding mode may be assigned on a CU level.

[0141] FIG. 7 illustrates an example of Partitioning of Coding Units into Prediction Units. The Partitioning of a Coding Unit into Prediction Unit(s) may be performed, for example, according to the partition type, which may be signaled in the bit-stream. An intra coding unit may use (e.g., only) the partition types 2Nx2N and NxN, as illustrated by example in FIG. 7. Square PUs (e.g., only square PUs) may be used in Intra Coding Units. Inter Coding Units may use square and / or rectangular partition types. For example, inter coding units may use (e.g., all) the partition types shown by example in FIG. 7.

[0142] Coding Units may (e.g., also) be divided into transform units in a recursive way, for example, following a “transform tree.” A transform tree may be a quad-tree division of a coding unit. Transform units may be the leaf nodes of the transform tree. A transform unit may encapsulate the square transform blocks of a (e.g., each) picture component associated with a considered square spatial area. A transform block may be a square block of samples in a single component, for example, where the same transform is applied.

[0143] A Coding Tree Unit representation in the compressed domain may represent picture data in a more flexible way. An advantage of flexible representation of the coding tree may be increased compression efficiency compared to the CU / PU / TU arrangement.

[0144] FIG. 8 illustrates an example of Quad-Tree Plus Binary-Tree (QTBT) CTU representation. A QTBT coding tool may provide the increased flexibility. A QTBT representation may include a coding tree, where coding units may be split in a quad-tree and / or in a binary-tree fashion.T1

[0145] The splitting of a coding unit may be decided on the encoder side, for example, based on (e.g., using) a rate distortion optimization procedure. The procedure may include determining the QTBT representation of the CTU with a minimal rate distortion cost.

[0146] A CU may be a square or rectangular shape in a QTBT representation. The size of coding unit may (e.g., always) be a power of two (2), such as between four (4) to 128.

[0147] A CTU representation may have one or more (e.g., all) of the following characteristics: a variety of rectangular shapes for a coding unit; QTBT decomposition of a CTU may be multiple (e.g., two) stages; Luma and Chroma block partitioning structure may be separated and / or decided independently in intra slices; a CU may not be partitioned into predictions units or transform units; an additional CU split mode may be implemented.

[0148] QTBT decomposition of a CTU may be performed in one or multiple (e.g., two) stages. For example, a CTU may (e.g., first) be split in a quad-tree fashion and a (e.g., each) quad-tree leaf may be further divided in a binary fashion, as shown by the example in FIG. 8, where solid lines may represent the quad-tree decomposition phase and dashed lines may represent the binary decomposition that is spatially embedded in the quad-tree leaves.

[0149] The Luma and Chroma block partitioning structure may be separated and / or decided independently in intra slices.

[0150] A CU may not be partitioned into predictions units or transform units. A (e.g., each) Coding Unit may be (e.g., systematically) made of a single prediction unit (e.g., previously 2Nx2N prediction unit partition type) and / or a single transform unit (e.g., no division into a transform tree).

[0151] In some examples, a CU may not be partitioned into PUs or TUs for most coding units and / or for most CU coding modes. A (e.g., each) Coding Unit may be (e.g., systematically) made of a single prediction unit (e.g., 2Nx2N prediction unit partition type) and / or a single transform unit (e.g., no division into a transform tree). There may be exceptions. For example, one or more of the following PU or TU partitioning may apply for coding units in one or more (e.g., four (4)) coding modes. A CU (e.g., larger than 64 in width or height) may be tiled into a TU of size equal to the maximum supported transform size. The maximum transform size may be equal to 64, for example. An intra CU coded in intra sub-partition (ISP) mode may be split into two (2) or four (4) transform units, for example, depending on the type of ISP mode used and / or the shape of the CU. An inter CU coded in sub-block transform (SBT) mode may be split into two (2) transform units, where one of the resulting TUs may have residual data equal to zero. An inter CU coded in Triangle Prediction Merge (TPM) mode may be made of two (2) triangular prediction units, where each PU may be assigned its own motion data.

[0152] An additional CU split mode may be implemented, which may be referred to as the horizontal of vertical triple tree splitting mode. The CU split mode may include dividing a coding unit (CU) into three (3) sub-coding-units (sub-CUs), which may have respective sizes equal toand % of the parent CU size, e.g., in the direction of the considered spatial division. An example of Horizontal (e.g., HOR_TRIPLE) and Vertical (e.g., VER_TRIPLE) Triple Tree Coding Unit splitting modes is illustrated in FIG. 9.

[0153] An example of a (e.g., complete) set of CU splitting modes present in a codec based on a video coding scheme is illustrated in FIG. 10.

[0154] Coding units having rectangular shapes may be used in a binary splitting mode (e.g., an asymmetric splitting mode), as shown in FIG. 11. These rectangular CU shapes may have a size that is 3 ■ 2nin width and / or height. A CU with a size that is a multiple of 3 in width and / or height may be split in a binary fashion, horizontally and / or vertically. A square coding unit with a size (w, h) (e.g., representing width and height) that is split through one or more asymmetric binary splitting modes (e.g., such as HORJJP or horizontal-up) may result in multiple (e.g., two) sub-coding units with respective rectangular sizes

[0155] FIG. 12 illustrates examples of partitions and CU split modes including horizontal and vertical triple tree split modes. A triple tree split may include splitting a CU into tree sub-CU with size (1 / 4, 1 / 2, 1 / 4) relative to a parent CU, in a considered orientation.

[0156] FIG. 13 illustrates examples of coding units that may be chosen by an encoder. The thick black square in the upper-right corner of FIG. 13 may represent a quad-tree decomposition of a CTU, while the thinner white lines inside the square may represent a binary-tree decomposition embedded into the quadtree. Triple tree and asymmetric binary tree split modes may be used to partition a picture as shown in FIG. 13. The coding unit topologies (e.g., additional coding unit topologies generated by the triple tree and asymmetric binary tree split modes) may allow for coding structures that may spatially match the structures and / or discontinuities included in a video signal.

[0157] An asymmetric binary tree (ABT) split mode may increase coding efficiency. ABT may introduce possibilities for recursively dividing a coding tree unit into coding units, which may enlarge the search space for finding a way (e.g., a best way) to divide a CTU into coding units. Coding runtime (e.g., encoder runtime) may increase as a result of the enlarged search space. To support a CU size of 3 ■ 2n(e.g., in width and / or height), non-power-of-two transform sizes may be used.

[0158] One or more split (e.g., block partitioning) modes described in this disclosure may achieve a trade-off between coding (e.g., encoding) time and compression performance, for example, withoutintroducing additional CU sizes. The performance of a video system may be improved using these split modes.

[0159] A block partitioning mode as described herein may be used to derive topologies that may not be available with other partitioning modes. For example, some block boundary positions obtained using a block partitioning mode as described herein may not be available with the other partitioning modes. A block partitioning mode described herein may be used to split a block area into multiple sub-blocks (e.g., 3, 4, or more) based on a single splitting operation.

[0160] A block partitioning mode as described herein may include a shifted quad-tree splitting mode. Using the shifted quad-tree splitting mode, a square or rectangular area may be split via quad-tree splitting. The split lines associated with the quad-tree splitting may or may not be located in the middle of a parent block.

[0161] The shifted quad-tree splitting mode may be associated with one or more enabling / disabling rules, which may ensure that a (e.g., any) coding tree leaf may include a rectangular or square block with a size (e.g., width and / or height) equal to a power of 2. An intermediate coding tree node with a non- dyadic block size (e.g., not equal to a power of 2) may be divided (e.g., recursively) into sub-blocks.

[0162] FIG. 14 illustrates an example syntax arrangement associated with signaling a block partition. One or more of the following syntax elements may be used (e.g., at a coding tree node level). A split_cu_flag may indicate if a block corresponding to a current coding tree node may be split. If the block is not split, a NO_SPLIT split mode may be assigned to the current block, which may include a leaf of the coding tree of a considered CTU. A split_qt_flag may indicate if a block corresponding to a current coding tree node may be quad-tree split. If the block is quad-tree split, a QT split mode may be assigned to the current coding tree node, and the corresponding picture block may be divided into multiple (e.g., 4) subblocks (e.g., of equal sizes). If the block is not quad-tree split, the current block may be split based on a binary or ternary tree split mode, and a following syntax element (e.g., mtt_sp I it_c u_vertical_flag) may be signaled. A mtt_sp I it_c u_vertical_flag may indicate if a binary or ternary split is applied to a current block along a vertical or horizontal direction. It may be followed by another syntax element (e.g., mtt_split_binary_flag). A mtt_split_bi nary_flag may indicate if the binary split is applied to a current block. If the binary split is not applied, a ternary split may be applied.

[0163] FIG. 15 illustrates an example of a shifted quad-tree splitting mode. The shifted quad-tree splitting mode may divide a block into multiple (e.g., 4) sub-CUs, where a point of intersection (e.g., split center) between vertical and horizontal split boundaries may be shifted relative to the center of a parentCU. For example, the split center may be located at an above-right, below-right, above-left, or below left position relative to the center of the parent CU.

[0164] FIG. 16 illustrates an example syntax arrangement associated with the shifted quad-tree splitting mode. One or more syntax elements may be used to signal the split mode of a given coding tree node. The syntax elements may include one or more of the following (e.g., if an indication such as a split_qt_fl ag is set to true). The syntax elements may include a split_qt_shifted_flag, which, if set to true, may indicate that the quad-tree splitting of a block is shifted relative to the center of a parent CU. If the split_qt_shifted_flag is set to false, a regular quad-tree split mode QT may be assigned to the block. If the split_qt_shifted_flag is set to true, one or more other syntax elements such as split_up_flag and sp lit Jeft_fl ag may be signaled. If set to true, the spl it_up_fl ag may indicate that the split center is located on top of a parent CU center. If set to false, the split_up_flag may indicate that the split center is located below the center of the parent CU. The split_left_flag, if set to true, may indicate that the split center is located on the left of the parent CU center. If set to false, the split Jeft_flag may indicate that the split center is located on the right of the parent CU center. Based on these syntax elements, a block partitioning may lead to multiple (e.g., 4) split modes including, for example, QT_UP_LEFT (e.g., upperleft), QT_UP_RIGHT (e.g., upper-right), QT_DOWN_LEFT (e.g., down-left), and / or QT_DOWN_RIGHT (e.g., down-right).

[0165] If shifted quad-tree splitting is applied for a current coding tree node, the corresponding block may be divided into multiple (e.g., 4) sub-blocks, e.g., as shown in FIG. 14 (e.g., using a QT_UP_RIGHT split mode). The partitioning may be applied as follows. A fixed split ratio (e.g., ae[0, 1 ]) may be used, which may, for example, allow for derivation of topologies that may not be available with other block partitioning techniques. In examples, a may be set to a value of 1 / 8 or 3 / 8.

[0166] The block division may be performed as follows (e.g., assuming a parent CU size of^parent Hparent)-

[0167] For the QT_UP_LEFT split mode, the four sub-blocks may be generated with respective sizes

[0168] For the QT_UP_RIGHT split mode, the four sub-blocks may be generated with respective sizes

[0169] For the QT_DOWN_LEFT split mode, the four sub-blocks may be generated with respective

[0170] For the QT_DOWN_RIGHT split mode, the four sub-blocks may be generated with respective

[0171] The value of a may be based on the size of a parent CU (e.g., based on the width and / or height of the parent CU, or the number of luma samples in the parent CU). The value of a may be based on the depth of a coding tree node corresponding to the parent CU.

[0172] Various block sizes may be used in a shifted quad-tree split mode, such as, e.g., 12, 24, 28, 40, 48, 56 or 80, depending on the value of parameter a.

[0173] One or more of the following may be true for the block partitioning mode(s) described herein (e.g., with respect to coding stages). Transform and / or inverse transform operations may support power- of-2 block sizes and non-power-of-2 block sizes (e.g., as in an asymmetric binary tree splitting mode). Block residual coding / decoding operations may be performed for coding unit sizes that are a multiple of 4.

[0174] Recursive splitting of coding tree nodes derived from a shifted quad-tree split may be applied. FIG. 18 shows an example of recursive splitting of a block based on a shifted quad-tree. The recursive splitting may avoid introducing new CU (e.g., coding tree leaf) sizes. Multiple (e.g., all) coding blocks (e.g., including a block resulting from a shifted quad-tree split) may have a size equal to a power of 2 (e.g., in width and / or height).

[0175] If a coding tree corresponds to a block has a size that is not a power of 2 (e.g., in width or height), the NO_SPLIT mode described herein may not be applied. A split indication (e.g., such as the split_cu_flag described herein) may not be signaled in this case and may be inferred to be true (e.g., to perform a split) at the decoder side. A horizontal or vertical binary split may be applied to a CU with a size that is not a power of 2 (e.g., in width or height).

[0176] If a binary split is applied in a direction in which the size is not a power of 2, the following may apply. If the binary split is not symmetric, the split ratio may be based on the non-power-of-2 size of the parent CU to be split. One or more of the following scenarios may occur. If the parent CU size has a form of 7 x 2n, the split ratios may be set to 3 / 7 and / or 4 / 7, which may lead to a non-power-of-2 subblock size and / or a power-of-2 sub-block size. If the parent CU size has a form of 5 x 2n, the split ratios may be set to 2 / 5 and / or 3 / 5, which may lead to a non-power-of-2 sub-block size and / or a power-of-2sub-block size. If the parent CU size has a form of 3 x 2n, the split ratios may be set to 1 / 3 and / or 2 / 3, which may lead to two power-of-2 sub-block sizes.

[0177] As an example, if a block with non-dyadic (e.g., non-power-of-2) width has a width equal to 28 (= - 8 x 32 = 7 x 22), a vertical binary split may lead to sub-block widths equal to 12 and 16. The sub- block having a width of 12 may be further split, with split ratios equal to 1 / 3 and / or 2 / 3, which may lead to 2 sub-blocks with sizes of 4 and 8, respectively.

[0178] As another example, for a non-symmetric binary splitting, one or more syntax elements may be signaled to indicate the arrangement of the non-symmetric split. FIG. 19 shows examples of these syntax elements. For example, if a horizontal binary split is applied, a bt_split_up_flag syntax element may be used to indicate if the binary split boundary is in the upper half of a parent block, which may lead to a split mode denoted BTJJP or a split mode denoted BTJDOWN. If a vertical binary split is applied, a bt_split_left_flag syntax element may be used to indicate if the binary split boundary is in the left half of the parent block, which may lead to a split mode denoted BT_LEFT or a split mode denoted BT_RIGHT.

[0179] As another example, symmetric and non-symmetric binary splits may be applied for a block with a non-dyadic size. The symmetric and non-symmetric binary splits may be applied (e.g., only) if subblocks resulted from the symmetric split may be further split into blocks with a dyadic size. For example, a block with a width of 24 may be symmetrically split into multiple (e.g., 2) sub-blocks with a width of 12. The two sub-blocks may be split into sub-blocks with sizes 4 and 8, respectively.

[0180] As shown in FIG. 20, a syntax element (e.g., bt_shifted_flag) may be used to indicate if a block is binary split in a symmetric way. If the block is not binary split in the symmetric way, another syntax element (e.g., bt_split_up_flag or bt_split_left_flag) may be signaled to indicate which non-symmetric binary split is applied.

[0181] As another example, a binary tree split and a quad-tree split may be applied to a block derived from shifted quad-tree splitting. FIG. 21 shows an example of applying a symmetric quad-tree split to a block resulting from shifted quad-tree splitting.

[0182] As another example, a quad-tree split of a block derived from a shifted quad-tree split may be performed in a way that may generate sub-blocks with dyadic sizes. FIG. 22 shows an example in which a QT_UP_RIGHT split mode may be applied (e.g., twice recursively) to an input square block. For example, a first shifted quad-tree split may apply split ratios of 3 / 4 and / or1 / 4 and a second shifted quadtree split may apply split ratios of 2 / 3 and / or 1 / 3. This may lead to a dyadic bottom right sub-block, as shown in FIG. 22. Other sub-blocks may employ a binary shifted split mode as described herein for end coding tree leaves having dyadic sizes.

[0183] As another example, a shifted quad-tree split may be applied to blocks with a size lower or equal to a threshold value (e.g., 64x64, 32x32 or 16x16). One or more constraints may be imposed under which a shifted quad-tree split may be applied (e.g., only) to square blocks.

[0184] As another example, a shifted non-square quad-tree (NOT) split may be extended to rectangular blocks, as shown in FIG. 23. The shifted non-square quad-tree splitting may divide 2NxN and / or Nx2N blocks into 4 sub-CUs, where the split center between the vertical and horizontal split boundaries may be shifted relative to the center of the parent CU.

[0185] As another example, multiple values of a split ratio a may be supported to perform a shifted quad-tree splitting of a given block. For example, the ratio a may be signaled in a bitstream after syntax elements split_qt_shifted_flag, split_up_flag and / or split_down_flag, such that a decoder may receive an indication of which shifted quad-split has been chosen and applied at an encoder side and the decode may perform a same split.

[0186] As another example, a separate shifted split ratio may be applied for vertical and / or horizontal split boundaries during a shifted quad-split operation. For example, two ratios ahorand avermay be signaled in a bitstream after syntax elements split_qt_shifted_flag, split_up_flag and / or split_down_flag, such that a decoder may receive an indication of which shifted quad-split has been chosen and applied at an encoder side and the decoder may perform a same split.

[0187] As another example, one (e.g., only one) of vertical and horizontal split boundaries may be shifted, which may result in one (e.g., only one) split ratio a being signaled in the bitstream and be applied to a corresponding vertical or horizontal split, as shown in FIG. 24.

[0188] As another example, for a given parent block to be split via a shifted quadtree, the shifted quadtree split may be adapted to comply with one or more constraints regarding the sizes of children blocks that may result from the split.

[0189] For example, if a Wparentx Hparentparent block is split via a shifted quadtree splitting mode, four children blocks may have sizes of c (l - Wparent) x aHparent, aWparentx aHparent, a(l - Wparent) x a(l - Hparent), and aWparentx a(l - Hparent), respectively. If a constraint is imposed that a block in a partitioning tree may not have a width smaller than 4 or a height smaller than 4, the shifted quadtree split may be adapted to avoid giving rise to children blocks with a width smaller than 4 or a height smaller than 4.

[0190] As shown in FIG. 25, if a Wparentx Hparentparent block is split via a shifted quadtree, it may result in two children blocks with sizes of (1 - Wparent) x aHparentand aWparentx aHparent > which may be invalid with respect to the constraint described above because their heightmay be smaller than 4. The other two children blocks with sizes a(l - Wparent) x a(l - Hparent) and aWparentx a(l - Hparentmay be valid with respect to the constraint. In this case, the shifted quadtree split may be transformed into a vertical binary split (e.g., by removing the horizontal part of the shifted quadtree split).

[0191] As shown in FIG. 26, if a Wparentx Hparentparent block is split via a shifted quadtree, it may result in two children blocks with sizes (1 - Wparent) x aHparentand a(l - Wparent) x a(l - Hparent), which may be invalid with respect to the constraint because their width is smaller than 4. The other two children blocks with sizes aWparentx aHparentand aWparentx c (l - Hparent) may be valid with respect to the constraint. In this case, the shifted quadtree split may be transformed into the horizontal binary split (e.g., removing the vertical part of the shifted quadtree split).

[0192] The adaption of a shifted quadtree split to comply with a constraint regarding the sizes of the children blocks arising from the split may be combined with a block partitioning syntax arrangement described herein (e.g., such as that of FIG. 16), for example, when only horizontal BT and vertical BT exist in the BT family. As another example, the adaptation of the shifted quadtree split to comply with the constraints regarding the sizes of the children blocks resulting from the split may be combined with any block partitioning syntax.

Claims

CLAIMS1. A video decoding device, comprising: a processor configured to: determine that a parent coding unit (CU) is to be partitioned into four or more sub-coding units (sub-CUs); determine whether to perform the partition based on a center of the parent CU; and if the determination is not to perform the partition based on the center of the parent CU, split the parent CU into the four or more sub-CUs along at least a first vertical split line and a first horizontal split line such that an intersection of the first vertical split line and the first horizontal split line is shifted away from the center of the parent CU.

2. The video decoding device of claim 1 , wherein the intersection of the first vertical split line and the first horizontal split line is located to the above-right of the center of the parent CU, the above-left of the center of the parent CU, the below-right of the center of the parent CU, or the below-left of the center of the parent CU.

3. The video decoding device of claim 1 or claim 2, wherein the determination of whether to perform the partition based on the center of the parent CU is made based on an indication received from a bitstream.

4. The video decoding device of claim 3, wherein the indication received from the bitstream indicates a position of the intersection of the first vertical split line and the first horizontal split line relative to the center of the parent CU.

5. The video decoding device of claim 3, wherein the indication received from the bitstream indicates a split ratio in at least one of a vertical direction or a horizontal direction.

6. The video decoding device of any claims 1-4, wherein the processor being configured to split the sub-CU along the second vertical split line and the second horizontal split line comprises the processor being configured to determine a split ratio in at least one of a vertical direction or a horizontal direction split ratio based on a size of the parent CU, a number of luma samples in the parent CU, or a depth level of a coding tree associated with of the parent CU.

7. The video decoding device of any of claims 1 -6, wherein the processor is further configured to: determine whether to partition a sub-CU of the four or more sub-CUs based on a center of the sub-CU; and if the determination is not to partition the sub-CU based on the center of the sub-CU, split the sub-CU along at least a second vertical split line and a second horizontal split line such that an intersection of the second vertical split line and the second horizontal split line is shifted away from the center of the sub-CU.

8. The video decoding device of claim 7, wherein the sub-CU has a height or a width that is not a power of 2, and wherein a CU obtained from splitting the sub-CU along the second vertical split line and the second horizontal split line has a height or a width that is a power of 2.

9. A video decoding method, comprising: determining that a parent coding unit (CU) is to be partitioned into four or more sub-coding units (sub-CUs); determining whether to perform the partition based on a center of the parent CU; and if the determination is not to perform the partition based on the center of the parent CU, splitting the parent CU into the four or more sub-CUs along at least a first vertical split line and a first horizontal split line such that an intersection of the first vertical split line and the first horizontal split line is shifted away from the center of the parent CU.

10. The video decoding method of claim 9, wherein the intersection of the first vertical split line and the first horizontal split line is located to the above-right of the center of the parent CU, the above-left of the center of the parent CU, the below-right of the center of the parent CU, or the below-left of the center of the parent CU.11 . The video decoding method of claim 9 or claim 10, wherein the determination of whether to perform the partition based on the center of the parent CU is made based on an indication received from a bitstream.

12. The video decoding method of claim 11 , wherein the indication received from the bitstream indicates a position of the intersection of the first vertical split line and the first horizontal split line relative to the center of the parent CU.

13. The video decoding method of claim 11 , wherein the indication received from the bitstream indicates a split ratio in at least one of a vertical direction or a horizontal direction.

14. The video decoding method of any claims 9-12, wherein splitting the sub-CU along the second vertical split line and the second horizontal split line comprises determining a split ratio in at least one of a vertical direction or a horizontal direction based on a size of the parent CU, a number of luma samples in the parent CU, or a depth level of a coding tree associated with of the parent CU.

15. The video decoding method of any of claims 9-14, further comprising: determining whether to partition a sub-CU of the four or more sub-CUs based on a center of the sub-CU; andif the determination is not to partition the sub-CU based on the center of the sub-CU, splitting the sub-CU along at least a second vertical split line and a second horizontal split line such that an intersection of the second vertical split line and the second horizontal split line is shifted away from the center of the sub-CU.

16. The video decoding method of claim 15, wherein the sub-CU has a height or a width that is not a power of 2, and wherein a CU obtained from splitting the sub-CU along the second vertical split line and the second horizontal split line has a height or a width that is a power of 2.

17. A video encoding device, comprising: a processor configured to: determine that a parent coding unit (CU) is to be partitioned into four or more sub-coding units (sub-CUs); determine whether to perform the partition based on a center of the parent CU; and if the determination is not to perform the partition based on the center of the parent CU, split the parent CU into the four or more sub-CUs along at least a first vertical split line and a first horizontal split line such that an intersection of the first vertical split line and the first horizontal split line is shifted away from the center of the parent CU.

18. The video encoding device of claim 17, wherein the intersection of the first vertical split line and the first horizontal split line is located to the above-right of the center of the parent CU, the above-left of the center of the parent CU, the below-right of the center of the parent CU, or the below-left of the center of the parent CU.

19. The video encoding device of claim 17 or claim 18, wherein the determination of whether to perform the partition based on the center of the parent CU is made based on an indication received from a bitstream, and wherein the indication indicates a split ratio in at least one of a vertical direction or a horizontal direction.

20. A video encoding method, comprising: determining that a parent coding unit (CU) is to be partitioned into four or more sub-coding units (sub-CUs); determining whether to perform the partition based on a center of the parent CU; and if the determination is not to perform the partition based on the center of the parent CU, split the parent CU into the four or more sub-CUs along at least a first vertical split line and a first horizontal split line such that an intersection of the first vertical split line and the first horizontal split line is shifted away from the center of the parent CU.

21. The video encoding device of claim 20, wherein the intersection of the first vertical split line and the first horizontal split line is located to the above-right of the center of the parent CU, the above-left of the center of the parent CU, the below-right of the center of the parent CU, or the below-left of the center of the parent CU.

22. The video encoding method of claim 20 or claim 21 , wherein the determination of whether to perform the partition based on the center of the parent CU is made based on an indication received from a bitstream, and wherein the indication indicates a split ratio in at least one of a vertical direction or a horizontal direction.

23. A computer program product stored on a non-transitory computer readable medium and comprising program code instructions for implementing the steps of a method according to any one of claims 9-16 or claims 20-22 when executed by a processor.

24. Video data comprising information representative of the parent coding unit encoded according to the method of any of claims 20-22.

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