Transform index determination

Abstract

Systems, methods, and tools associated with transform coding are disclosed herein. Candidate transforms for a video block may be ranked by a video encoder based on respective hypothetical costs associated with processing the video block based on the candidate transforms. Transform index values indicating positions of appropriate transforms on the ranked list of transforms may then be signaled to a video decoder, the video decoder may perform a similar cost-based ranking operation to derive the ranked list of transforms and select a transform for the video block from the ranked list of transforms based on the signaled index.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of European Patent Application No. 22305494.1 filed on April 8, 2022, the contents of which are incorporated herein by reference. Background Art

[0003] Transform coding can be applied during video signal processing. Through transform coding, the prediction residual can be compressed into transform coefficients, which can use a smaller number of bits. Improvements to the transform coding process can lead to improved video coding performance. Summary of the invention

[0004] Systems, methods and tools associated with transform coding are disclosed herein. According to an embodiment of the present disclosure, a video decoding device may include a processor configured to obtain a transform index value that may indicate a position of a transform that can be used for a video block on a sorted transform list. The processor may be further configured to determine corresponding hypothetical costs associated with applying multiple transforms to the video block, and the multiple transforms may be sorted according to the determined hypothetical costs to derive the sorted transform list. The processor may be configured to select a transform for the video block based on the sorted transform list and the transform index value, and may decode the video block based at least on the selected transform.

[0005] According to an embodiment of the present disclosure, a video encoding device may include a processor configured to determine corresponding assumed costs associated with applying multiple transforms to a video block, and to sort the multiple transforms according to the determined assumed costs. The processor may be configured to: obtain a sorted transform list according to the sorting result; select a transform for the video block (e.g., based on a decoding cost including the determined assumed costs associated with the multiple transforms and / or decoding efficiency considerations); and determine a transform index value associated with the selected transform based on the sorted transform list. Such a transform index value may (for example) indicate the position of the selected transform on the sorted transform list. The processor of the video encoding device may be further configured to encode a video block in the video data based at least on the selected transform, and to encode an indication of the transform index value in the video data.

[0006] In some examples, the transform may include two or more multiple transform selection (MTS) transforms and / or discrete cosine transforms, while in other examples, the transform may include two or more low frequency non-separable transforms (LFNSTs). In some examples, a corresponding hypothetical cost associated with applying the transform to a video block may be determined based on samples of the video block and one or more rows and / or columns of neighboring video blocks. For example, the corresponding hypothetical cost for the transform may be determined based on continuity or discontinuity between samples in the video block and neighboring samples that may be caused by applying the transform to the video block. In an example, the transform index value may be obtained by encoding or decoding a binarization code for the transform index value, wherein parameters for encoding or decoding the binarization code may depend on the number of transforms on the sorted transform list.

[0007] In some examples, the video encoding device and / or video decoding device described herein may be configured to determine corresponding hypothetical costs associated with applying multiple transforms to a video block, and predict the transform to be applied to the video block based on the determined hypothetical costs. In an example, the video encoding device and / or video decoding device may be configured to use a predicted transform, while in other examples, the video encoding device and / or video decoding device may be configured to further determine a difference between a corresponding transform index associated with the predicted transform and an actual transform to be applied, and select the actual transform based at least on the difference. The difference may be signaled by the video encoding device in the video data and received by the video decoding device. An indication of the execution of the transform index prediction may also be signaled in the video data.

[0008] The systems, methods, and tools described herein may include a video encoder, a video decoder, and / or a computer-readable medium which may include instructions for causing a processor to perform the operations described herein. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0010] Figure 1B is an example of a method that can be used according to an embodiment of the present invention. Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within an illustrated communication system.

[0011] Figure 1C is an example of a method that can be used according to an embodiment of the present invention. Figure 1A System diagram of an example Radio Access Network (RAN) and an example Core Network (CN) for use within the illustrated communication system.

[0012] Figure 1D is an example of a method that can be used according to an embodiment of the present invention. Figure 1A System diagram of yet another example RAN and yet another example CN for use within the illustrated communication system.

[0013] Figure 2 is a diagram illustrating an example video encoder.

[0014] Figure 3 is a diagram illustrating an example video decoder.

[0015] Figure 4 is a diagram illustrating an example of a system in which various aspects and examples may be implemented.

[0016] Figure 5 is a diagram illustrating an example of a region of interest (ROI) associated with a transform coding mode.

[0017] Figure 6 is a diagram illustrating another example of a ROI associated with a transform coding mode.

[0018] Figure 7 is a diagram illustrating an example of using a block discontinuity measure as a cost function for predicting and / or reordering transforms.

[0019] Figure 8 is a diagram illustrating an example of cost-based transformation ordering. DETAILED DESCRIPTION

[0020] A more detailed understanding may be obtained from the following description given by way of example in conjunction with the accompanying drawings.

[0021] Figure 1A 1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). For example, the communication system 100 may employ one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), 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 multi-carrier (FBMC), etc.

[0022] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, Internet 110 and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a “station” and / or “STA”) may be configured to send and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0023] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device that is 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 other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an eNode B, a Home Node B, a Home eNode B, a gNB, an NR Node B, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0024] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. The base station 114a and / or the base station 114b may be configured to send and / or receive wireless signals on one or more carrier frequencies (which may be referred to as cells (not shown)). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrums. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, a cell associated with the base station 114a may be divided into three sectors. Therefore, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to send and / or receive signals in a desired spatial direction.

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

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

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

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

[0029] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may together implement LTE radio access and NR radio access, for example using the dual connectivity (DC) principle. Thus, the air interface used by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

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

[0031] Figure 1AThe base station 114b in the may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a business location, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology (such as IEEE 802.11) to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology (such as IEEE 802.15) to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or a femtocell. As Figure 1A As shown, base station 114b may have a direct connection to Internet 110. Therefore, base station 114b may not need to access Internet 110 via CN 106 / 115.

[0032] The RAN 104 / 113 may be in communication with the CN 106 / 115, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform advanced security functions, such as user authentication. Although not described in detail in the text, the CN 106 / 115 may be configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform advanced security functions, such as user authentication. Figure 1A Although not shown in the figure, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0033] The CN 106 / 115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired communication networks and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 / 113 or a different RAT.

[0034] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0035] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

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

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

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

[0039] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

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

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

[0042] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0043] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, module, a frequency modulation (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, etc. Peripheral device 138 may include one or more sensors, which may be one or more of the following: a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0044] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference via signal processing performed by hardware (e.g., a choke) or via a processor (e.g., a separate processor (not shown) or via the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) or downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0045] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0046] The RAN 104 may include evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the evolved Node-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the evolved Node-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0047] Each of the evolved Node Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, etc. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0048] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements is depicted as being part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0049] The MME 162 may be connected to each of the evolved Node-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0050] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during inter-evolved Node-B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0051] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0052] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may be in communication with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers.

[0053] Although the WTRU Figures 1A to 1D Although described as wireless terminals, it is contemplated that in certain representative embodiments, such terminals may (eg, temporarily or permanently) use a wired communications interface with a communications network.

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

[0055] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STA) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or carries traffic away from the BSS. Traffic originating from outside the BSS and leading to the STA may be reached by the AP and may be delivered to the STA. Traffic originating from the STA and leading to a destination outside the BSS may be transmitted to the AP to be delivered to the corresponding destination. Traffic between STAs within the BSS may be transmitted by the AP, for example, wherein the source STA may transmit traffic to the AP, and the AP may transmit traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. Direct link establishment (DLS) may be utilized to transmit point-to-point traffic between the source STA and the destination STA (e.g., directly between them). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (eg, all STAs in the STA) may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0056] When using the 802.11ac infrastructure operating mode or a similar operating mode, the AP may send beacons on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a width dynamically set via signaling. The primary channel may be an operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may listen to the primary channel. In the case where the primary channel is listened / detected and / or determined to be busy by a specific STA, the specific STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0057] High throughput (HT) STAs may communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0058] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining continuous 20MHz channels. 160MHz channels can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and data can be sent by the transmitter STA. At the receiver of the receiver STA, the above-mentioned operation for the 80+80 configuration can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0059] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support instrument type control / machine type communications, such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0060] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA (which supports the minimum bandwidth operating mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because a STA (supporting only a 1MHz operating mode) is sending to the AP, the entire available frequency band may be considered busy even if most of the frequency bands remain idle and may be available.

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

[0062] Figure 1D 1 is a system diagram illustrating the RAN 113 and the CN 115 in accordance with an embodiment. As noted above, the RAN 113 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0063] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b may utilize beamforming to send signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to send wireless signals to and / or receive wireless signals from the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0064] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with parameter sets that may be scalable. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or Transmission Time Intervals (TTIs) of varying or scalable lengths (e.g., containing varying numbers of OFDM symbols and / or varying absolute time lengths over time).

[0065] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchors. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as the eNode-B 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-B 160a, 160b, 160c may act as a mobility anchor for the WTRUs 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0066] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b, routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0067] Figure 1DThe illustrated CN 115 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although each of the foregoing elements is depicted as part of the CN 115, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0068] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different PDU sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of NAS signaling, mobility management, etc. The AMF 182a, 182b may use network slicing in order to customize CN support for the WTRU 102a, 102b, 102c based on the type of services utilized by the WTRU 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced mobile broadband (eMBB) access, services for machine type communication (MTC) access, etc. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0069] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 115 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 115 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and configure the traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0070] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, etc.

[0071] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b via the UPF 184a, 184b via an N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0072] Given that Figures 1A to 1D as well as Figures 1A to 1D Corresponding to the description of the present invention, one or more or all of the functions described herein with reference to one or more of the following may be performed by one or more simulation devices (not shown): WTRU102a-d, base station 114a-b, evolved Node B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b and / or any other device described herein. The simulation device may be one or more devices configured to emulate one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

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

[0074] One or more simulation devices can perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used in a test scenario in a test laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. One or more simulation devices can be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (e.g., which can include one or more antennas) can be used by the simulation device to send and / or receive data.

[0075] The present application describes a number of aspects, including tools, features, examples, models, methods, etc. Many of these aspects are described in a particular manner, and at least in order to illustrate individual features, are usually described in a manner that may sound restrictive. However, this is to describe clearly and does not limit the application or scope of these aspects. In fact, all different aspects can be combined and interchanged to provide further aspects. In addition, these aspects can also be combined and interchanged with the aspects described in the earlier submission.

[0076] The aspects described and contemplated in this application can be implemented in many different forms. Figures 5 to 7 Some examples may be provided, but others are also contemplated. Figures 5 to 7 The discussion does not limit the breadth of specific implementations. At least one of these aspects generally relates to video encoding and decoding, and at least one other aspect generally relates to sending a generated or encoded bitstream. These and other aspects may be implemented as methods, apparatus, computer-readable media (e.g., storage media) including (e.g., having stored thereon) instructions for encoding or decoding video data according to any of the described methods, and / or computer-readable storage media having stored thereon a bitstream generated according to any of the described methods.

[0077] In this application, the terms "reconstruction" and "decoding" may be used interchangeably, the terms "pixel" and "sample" may be used interchangeably, and the terms "image", "picture" and "frame" may be used interchangeably.

[0078] Various methods are described herein, and each method includes one or more steps or actions for implementing the method. Unless the correct operation method requires a specific order of steps or actions, the order and / or purpose of specific steps and / or actions can be modified or combined. In addition, in various examples, terms such as "first", "second" and the like can be used to modify elements, parts, steps, operations, etc., such as "first decoding" and "second decoding". Unless specifically required, the use of such terms does not imply the ordering of the modification operation. Therefore, in this example, the first decoding does not need to be performed before the second decoding, and can, for example, occur before, during, or in an overlapping time period of the second decoding.

[0079] like Figure 2 and Figure 3 As shown, various methods and other aspects described in this application can be used to modify modules (e.g., decoding modules) of video encoder 200 and decoder 300. In addition, the subject matter disclosed herein can be applied to, for example, any type, format, or version of video decoding (whether described in a standard or described in a recommendation), whether pre-existing or developed in the future, as well as extensions of any such standards and recommendations. Unless otherwise indicated or technically excluded, the aspects described in this application can be used alone or in combination.

[0080] Various numerical values ​​are used in the examples described in this application, such as the number of transform pairs, etc. These and other specific values ​​are used for the purpose of describing the examples, and the described aspects are not limited to these specific values.

[0081] Figure 2 is a diagram illustrating an example video encoder. Variations of the example encoder 200 are contemplated, but the following describes encoder 200 for clarity without describing all contemplated variations.

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

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

[0084] The prediction residual is then transformed 225 and quantized 230. The quantized transform coefficients, along with motion vectors and other syntax elements, are entropy coded 245 to output a bitstream. The encoder may skip the transform and apply quantization directly to the untransformed residual signal. The encoder may bypass both the transform and quantization, i.e., directly code the residual without applying the transform or quantization process.

[0085] The encoder decodes the coded block to provide a reference for further prediction. The quantized transform coefficients are dequantized 240 and inverse transformed 250 to decode the prediction residual. The decoded prediction residual and the prediction block are combined 255 to reconstruct the image block. An in-loop filter 265 is applied to the reconstructed picture to perform, for example, deblocking / SAO (sample adaptive offset) filtering to reduce coding artifacts. The filtered image is stored at the reference picture buffer (280).

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

[0087] Specifically, the input of the decoder includes a video bitstream, which may be generated by the video encoder 200. First, the bitstream is entropy decoded 330 to obtain transform coefficients, motion vectors, and other decoding information. The picture partition information indicates how the picture is partitioned. Therefore, the decoder can divide 335 the picture according to the decoded picture partition information. The transform coefficients are dequantized 340 and inverse transformed 350 to decode the prediction residual. The decoded prediction residual and the prediction block are combined 355 to reconstruct the image block. The prediction block can be obtained 370 from intra-frame prediction 360 or motion compensated prediction (i.e., inter-frame prediction) 375. An in-loop filter 365 is applied to the reconstructed image. The filtered image is stored at the reference picture buffer 380.

[0088] The decoded picture may also undergo post-decoding processing 385, such as an inverse color transform (e.g., conversion from YCbCr 4:2:0 to RGB 4:4:4), or an inverse remapping that performs the inverse of the remapping process performed in the pre-encoding process 201. The post-decoding processing may use metadata derived in the pre-encoding process and signaled in the bitstream. In an example, the decoded image (e.g., after applying the in-loop filter 365 and / or after the post-decoding processing 385, if a post-decoding process is used) may be transmitted to a display device for presentation to a user.

[0089] Figure 4 4 is a diagram showing an example of a system in which various aspects and examples described herein can be implemented. System 400 may be embodied as a device including various components described below and configured to perform one or more aspects 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, smart phones, tablet computers, digital multimedia set-top boxes, digital television receivers, personal video recording systems, connected home appliances, and servers. The elements of system 400 may be embodied in a single integrated circuit (IC), multiple ICs, and / or discrete components, either individually or in combination. For example, in at least one example, the processing and encoder / decoder elements of system 400 are distributed over multiple ICs and / or discrete components. In various examples, system 400 is communicatively coupled to one or more other systems or other electronic devices via, for example, a communication bus or through dedicated input ports and / or output ports. In various examples, system 400 is configured to implement one or more aspects of the aspects described in this document.

[0090] The system 400 includes at least one processor 410 configured to execute instructions loaded therein for implementing, for example, various aspects described in this document. The processor 410 may include embedded memory, input-output interfaces, and various other circuits 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). The system 400 includes a storage device 440, which may include a non-volatile memory and / or a volatile memory, including but not limited to an electrically erasable programmable read-only memory (EEPROM), a read-only memory (ROM), a programmable read-only memory (PROM), a random access memory (RAM), a dynamic random access memory (DRAM), a static random access memory (SRAM), a flash memory, a magnetic disk drive, and / or an optical disk drive. As non-limiting examples, the storage device 440 may include an internal storage device, an attached storage device (including a removable and non-removable storage device), and / or a network-accessible storage device.

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

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

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

[0094] Inputs to the elements of system 400 may be provided through various input devices as indicated in block 445. Such input devices include, but are not limited to: (i) a radio frequency (RF) section that receives an RF signal, such as that transmitted 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 ( Figure 4 ) includes composite video.

[0095] In various examples, the input device of frame 445 has the corresponding input processing element associated as known in the art.For example, the RF part can be associated with the element suitable for the following: (i) select the required frequency (also referred to as selecting signal, or limiting the signal band to a band), (ii) down-convert the selected signal, (iii) again band-limit to narrower band to select the signal band that (for example) can be called channel in some examples, (iv) demodulate the signal of down-conversion and band-limitation, (v) perform error correction, and / or (vi) demultiplex to select the required data packet stream.The RF part of various examples includes one or more elements for performing these functions, such as frequency selector, signal selector, band limiter, channel selector, filter, down-converter, demodulator, error corrector and demultiplexer.The RF part can include the tuner of various functions that perform these functions, and these functions include, for example, down-converting the received signal to a lower frequency (for example, intermediate frequency or near baseband frequency) or to baseband. In a set-top box example, the RF part and its associated input processing element receive the RF signal sent by wired (for example, cable) medium, and filter to the desired frequency band by filtering, down-conversion and again to perform frequency selection.Various examples rearrange the order of above-mentioned (and other) elements, remove some elements in these elements, and / or add other elements that perform similar or different functions.Adding element can include inserting element between existing elements, for example, inserting amplifier and analog-to-digital converter.In various examples, the RF part includes antenna.

[0096] The USB and / or HDMI terminals may include corresponding interface processors for connecting the system 400 to other electronic devices across the USB and / or HDMI connections. It should be understood that various aspects of input processing (e.g., Reed-Solomon error correction) may be implemented as needed, for example, in a separate input processing IC or in the processor 410. Similarly, various aspects of USB or HDMI interface processing may be implemented as needed in a separate interface IC or in the processor 410. The demodulated, error-corrected, and demultiplexed streams are provided to various processing elements, including, for example, the processor 410 and the encoder / decoder 430, which operate in conjunction with the memory and storage elements to process the data streams as needed for presentation on the output device.

[0097] The various components of system 400 may be disposed within an integrated housing. Within the integrated housing, the various components may be interconnected and transmit data between the components using a suitable connection arrangement 425 (e.g., an internal bus known in the art, including an inter-chip (I2C) bus, wiring, and a printed circuit board).

[0098] System 400 includes a communication interface 450 that enables communication with other devices via a communication channel 460. Communication interface 450 may include, but is not limited to, a transceiver configured to send and receive data through communication channel 460. Communication interface 450 may include, but is not limited to, a modem or a network card, and communication channel 460 may be implemented, for example, within a wired and / or wireless medium.

[0099] In various examples, data is streamed or otherwise provided to the system 400 using a wireless network, such as a Wi-Fi network, e.g., IEEE 802.11 (IEEE refers to the Institute of Electrical and Electronics Engineers). The Wi-Fi signals of these examples are received via a communication channel 460 and a communication interface 450 suitable for Wi-Fi communications. The communication channel 460 of these examples is typically connected to an access point or router that provides access to external networks, including the Internet, to allow streaming applications and other cross-top communications. Other examples provide streaming data to the system 400 using a set-top box that delivers data via an HDMI connection of an input box 445. Still other examples use an RF connection of an input box 445 to provide streaming data to the system 400. As described above, various examples provide data in a non-streaming manner. Additionally, various examples use wireless networks other than Wi-Fi, such as cellular networks or network.

[0100] The system 400 may provide output signals to various output devices, including a display 475, a speaker 485, and other peripherals 495. The display 475 of various examples includes, for example, one or more of a touch screen display, an organic light emitting diode (OLED) display, a curved display, and / or a foldable display. The display 475 may be used for a television, a tablet computer, a laptop, a cellular phone (mobile phone), or other devices. The display 475 may also be integrated with other components (e.g., as in a smart phone), or may be independent (e.g., an external monitor for a laptop computer). In various examples, other peripherals 495 include one or more of an independent digital video disc (or digital versatile disc) (DVD, for both terms), a disc player, a stereo system, and / or a lighting system. Various examples use one or more peripherals 495 that provide functions based on the output of the system 400. For example, a disc player performs the function of playing the output of the system 400.

[0101] In various examples, control signals are transmitted between the system 400 and the display 475, speaker 485, or other peripheral device 495 using signaling such as AV.Link, consumer electronics control (CEC), or other communication protocols that enable device-to-device control with or without user intervention. Output devices may be communicatively coupled to the system 400 via dedicated connections through respective interfaces 470, 480, and 490. Alternatively, the output devices may be connected to the system 400 via a communication interface 450 using a communication channel 460. The display 475 and speaker 485 may be integrated into a single unit with other components of the 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 (TCon) chip.

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

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

[0104] Various implementations include decoding. As used herein, "decoding" may encompass, for example, all or part of a process performed on a received coded sequence 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, such as entropy decoding, inverse quantization, inverse transform, and differential decoding. In various examples, such processes also include or alternatively include processes performed by a decoder of various implementations described herein.

[0105] As another example, in one example, "decoding" refers only to entropy decoding, in another example, "decoding" refers only to differential decoding, and in another example, "decoding" refers to a combination of entropy decoding and differential decoding. Whether the phrase "decoding process" is intended to refer specifically to a subset of operations or broadly to a broader decoding process will be clear based on the context of the specific description and is considered to be well understood by those skilled in the art.

[0106] Various implementations include encoding. In a manner similar to the discussion above regarding "decoding", "encoding" as used in this application may encompass, for example, all or part of a process performed on an input video sequence to produce an encoded bitstream. In various examples, such processes include one or more of the processes typically performed by an encoder, such as partitioning, differential encoding, transforms, quantization, and entropy encoding. In various examples, such processes also include or alternatively include processes performed by encoders of various implementations described in this application, such as transform index prediction, transform index reordering, etc.

[0107] As another example, 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 decoding and entropy encoding. Whether the phrase "encoding process" specifically refers to a subset of operations or broadly refers to a broader encoding process will be clear based on the context of the specific description and is believed to be well understood by those skilled in the art.

[0108] It should be noted that the syntax elements used herein (such as cu_predicted_mts_idx_flag, etc.) are descriptive terms. Therefore, they do not exclude the use of other syntax element names.

[0109] When the figures are presented as flow charts, it should be understood that they also provide block diagrams of corresponding devices. Similarly, when the figures are presented as block diagrams, it should be understood that they also provide flow charts of corresponding methods / processes.

[0110] The specific implementations and aspects described herein may be implemented in, for example, a method or process, a device, a software program, a data stream, or a signal. Even if only discussed in the context of a single form of specific implementation (e.g., discussed only as a method), the specific implementation of the features discussed may also be implemented in other forms (e.g., a device or program). The device may be implemented in, for example, appropriate hardware, software, and firmware. These methods may be implemented in, for example, a processor, which generally refers to a processing device, including, for example, a computer, a microprocessor, an integrated circuit, or a programmable logic device. The processor also includes communication equipment, such as, for example, a computer, a mobile phone, a portable / personal digital assistant ("PDA"), and other equipment that facilitates information communication between end users.

[0111] References to "one example" or "an example" or "one implementation" or "an implementation" and other variations thereof mean that a particular feature, structure, characteristic, etc. described in connection with the example is included in at least one example. Thus, the phrases "in one example" or "in an example" or "in one implementation" or "in an implementation" and any other variations appearing in various places throughout this application are not necessarily all referring to the same example.

[0112] Additionally, the present application may involve "determining" various pieces of information. Determining information may include, for example, one or more of estimating information, calculating information, predicting information, or retrieving information from a memory. Obtaining may include receiving, retrieving, constructing, generating, and / or determining.

[0113] Furthermore, the present application may refer to "accessing" various information. Accessing information may include, for example, one or more of receiving information, retrieving information (e.g., from a memory), storing information, moving information, copying information, calculating information, determining information, predicting information, or estimating information.

[0114] Additionally, the present application may refer to "receiving" various information. Like "accessing," receiving is intended to be a broad term. Receiving information may include, for example, one or more of accessing information or retrieving information (e.g., from a memory). Furthermore, "receiving" generally involves, in one way or another, during operations such as, for example, storing information, processing information, sending information, moving information, copying information, erasing information, calculating information, determining information, predicting information, or estimating information.

[0115] It should be understood that, for example, in the case of "A / B," "A and / or B," and "at least one of A and B," the use of any of the following " / ," "and / or," and "at least one of" is intended to encompass selecting only the first listed option (A), or only the second listed option (B), or both options (A and B). As a further example, in the case of "A, B, and / or C" and "at least one of A, B, and C," such phrases are intended to encompass selecting only the first listed option (A), or only the second listed option (B), or only the third listed option (C), or only the first listed option and the second listed option (A and B), or only the first listed option and the third listed option (A and C), or only the second listed option and the third listed option (B and C), or all three options (A and B and C). This can be extended to as many items as listed, as will be apparent to one of ordinary skill in this and related arts.

[0116] Moreover, as used herein, the term "signaling" refers to (among other things) indicating something to a corresponding decoder. Thus, in one example, the same parameters are used on both the encoder side and the decoder side. Thus, for example, the encoder may send (explicit signaling) specific parameters to the decoder so that the decoder may use the same specific parameters. On the contrary, if the decoder already has specific parameters and other parameters, signaling may be used without sending (implicit signaling) to simply allow the decoder to know and select specific parameters. Bit savings are achieved in various examples by avoiding sending any actual function. It should be understood that signaling can be implemented in a variety of ways. For example, in various examples, one or more syntax elements, flags, etc. are used to signal information to the corresponding decoder. Although the verb form of the term "signaling" is mentioned above, the term "signal" may also be used as a noun herein.

[0117] It will be apparent to one of ordinary skill in the art that a specific implementation may generate a variety of signals formatted to carry, for example, storable or transmittable information. The information may include, for example, instructions for executing a method or data generated by one of the described specific implementations. For example, a signal may be formatted to carry a bit stream of the example. Such a signal may be formatted as, for example, an electromagnetic wave (e.g., using a radio frequency portion of a spectrum) or a baseband signal. Formatting may include, for example, encoding a data stream and modulating a carrier using the encoded data stream. The information carried by the signal may be, for example, analog or digital information. As is well known, the signal may be sent over a variety of different wired or wireless links. The signal may be stored on, or accessed or received from, a processor-readable medium.

[0118] Many examples are described herein. The features of the examples may be provided individually or in any combination across various claim categories and types. In addition, the examples may include one or more of the features, devices or aspects described herein across various claim categories and types individually or in any combination. For example, the features described herein may include a bitstream or signal of information generated as described herein to be implemented. This information may allow a decoder to decode a bitstream, an encoder, a bitstream and / or a decoder according to any of the embodiments described in the embodiments. For example, the features described herein may be implemented by creating and / or sending and / or receiving and / or decoding a bitstream or a signal. For example, the features described herein may be implemented by a method, a process, a device, a medium storing instructions (e.g., a computer-readable medium), a medium storing data or a signal. For example, the features described herein may be implemented by a TV, a set-top box, a mobile phone, a tablet computer or other electronic devices that perform decoding. A TV, a set-top box, a mobile phone, a tablet computer or other electronic devices may display (e.g., using a monitor, a screen or other type of display) the resulting image (e.g., an image reconstructed from the residual of a video bitstream). A TV, a set-top box, a mobile phone, a tablet computer or other electronic devices may receive a signal including an encoded image and perform decoding.

[0119] Transform decoding can be performed in multiple stages including, for example, a primary transform and a secondary transform. A primary transform can expand a single-core transform (e.g., such as a type II discrete cosine transform (DCT-II)) with one or more other triangular transforms (e.g., such as a type VIII DCT (DCT-VIII) and / or a type VII discrete sine transform (DST-VII)) to compress residuals of different statistical values. The transform coefficients (e.g., 2D transform coefficients) obtained based on the primary transform can be further transformed (e.g., in an inseparable manner and / or by enabling a low-frequency non-separable transform (LFNST)), for example, using one or more pre-trained transform matrices to further compress the video signal (e.g., video content).

[0120] In an example, multiple transform selection (MTS) and / or LFNST may be extended with one or more additional transform matrices. The sign of the transform coefficient may be predicted by a transform sign prediction process. Such a process may test multiple (e.g., all) possible hypotheses about the value of the sign (e.g., positive or negative) of (e.g., each) transform coefficient, perform reconstruction of the current block, and compare the predicted samples and residual values ​​for the current block with the reconstructed neighboring samples to determine a cost or distance based on the predicted samples for the current block, the residual values ​​for the current block, and the reconstructed neighboring samples. The hypothesis that minimizes the cost or distance may be considered a valid (e.g., best) prediction of the symbol, and the difference between the predicted symbol and the actual symbol may be signaled (e.g., in place of the actual symbol).

[0121] For example, the index of the MTS and / or LFNST to be applied may be predicted in a manner similar to the transform symbols. The prediction of the MTS and / or LFNST index (e.g., the prediction of which MTS and / or LFNST may be applied) may result in improved coding performance, for example, because less information may need to be coded and / or signaled due to the prediction. For example, if the encoder and decoder can predict which transform may be applied to the current video block by the other side in a consistent manner (e.g., based on the costs associated with the various candidate transforms), then there may be no need to signal in the video bitstream or there may be no need to retrieve the transform index from the video bitstream.

[0122] In an example, the encoder and / or decoder may adopt DCT5, DST4, DST1 and / or an identity transform (IDT) as a primary transform, for example, in addition to or instead of an MTS transform. The set of available MTS transforms may depend on the transform unit (TU) size and / or intra-frame mode information. The MTS index may be coded using a truncated binary code (e.g., bypassing context-based coding). Multiple (e.g., 16) different TU sizes may be considered, and for one (e.g., each) TU size, multiple (e.g., 5) categories (e.g., different transform kernels or matrices) may be considered based on intra-frame mode information. The number of MTS candidates (e.g., 1, 4, or 6 MTS candidates) may be considered based on the sum of the absolute values ​​of the transform coefficients (e.g., coeff). For example, two thresholds (e.g., th1 and th2) may be specified (e.g., at the sequence parameter set (SPS) level) so that the number of MTS candidates may be determined based on the following items:

[0123]

[0124] The number of LFNST sets (S) and LFNST candidates (C) can be extended to, for example, S = 35 and C = 3. The LFNST set (e.g., indicated by a bitstream syntax element such as lfnstTrSetIdx) for a given intra mode (e.g., indicated by a bitstream syntax element such as predModeIntra) can be derived according to the following:

[0125] For predModeIntra<2, lfnstTrSetIdx=2;

[0126] For predModeIntra in [0,34], lfnstTrSetIdx = predModeIntra;

[0127] For predModeIntra in [35,66], lfnstTrSetIdx = 68 - predModeIntra

[0128] Multiple (e.g., three) cores such as LFNST4, LFNST8, and LFNST16 may be defined to indicate LFNST core sets. These LFNST core sets may be applied to transform unit sizes of 4×N / N×4 (N≥4), 8×N / N×8 (N≥8), and M×N (M, N≥16), respectively. The size of the core may be specified by:

[0129] (LFSNT4,LFNST8*,LFNST16*)=(16×16,32×64,32×96)

[0130] Forward LFNST may be applied to an upper left low frequency region of a video block, which may be referred to as a region of interest (ROI).When LFNST is applied, coefficients obtained from a primary transform and associated with a region other than the ROI may be zeroed.

[0131] Figure 5 An example of a ROI for LFNST16 is illustrated. The ROI may include six 4×4 sub-blocks (eg, shown as Figure 5 ), these sub-blocks may be continuous in scanning order. Based on such ROI, the number of input samples of forward LFNST16 may be 96, and the transformation matrix for forward LFNST16 may be R×96, where R may be set to 32 or another suitable value. If R is set to 32, 32 coefficients (e.g., two 4×4 sub-blocks) may be generated from forward LFNST16, and these coefficients may be placed following the coefficient scanning order.

[0132] Figure 6 An example of a ROI for LFNST8 is illustrated. For forward LFNST8, the transformation matrix may be R×64, where R may be set to 32 or another suitable value, and the coefficients generated using these values ​​or settings may be positioned in the same or substantially similar manner as LFNST16.

[0133] The following Table 1 illustrates an example of mapping from intra prediction modes to LFNST index sets.

[0134] Table 1 - Example mapping between intra prediction modes and LFNST set indices

[0135]

[0136] Parameters associated with transform coding (such as MTS and / or LFNST) may be signaled at the coding unit (CU) level. Table 2 illustrates an example syntax that may be used for signaling.

[0137] Table 2 - Syntax associated with MTS / LFNST signaling

[0138]

[0139] Transforms such as MTS and / or LFNST transforms may be applied to the coding unit. In an example, if the LFNST index signaled in the video data (e.g., a video bitstream) is not equal to zero, then the signaling of the MTS index may be skipped or bypassed in the video data, and the MTS index may be inferred to have a value of zero. For at least the MTS transform, truncated Rice binarization may be applied to determine the index of the transform, for example, as illustrated in Table 3 below.

[0140] Table 3 - Example binarization table for MTS index

[0141] mts_idx Bin 0 0 1 10 2 110 3 1110 4 1111

[0142] For the LFNST transform, the index of the LFNST transform may be determined using the same or similar binarization technique as used for the MTS transform, for example, as illustrated in Table 4 below.

[0143] Table 4 - Example binarization table for LFNST index

[0144] lfnst_idx Bin 0 0 1 10 2 110 3 111

[0145] In an example, a fixed number of bits (eg, two bits) may be used to code the LFNST transform index, eg, as illustrated in Table 5 below.

[0146] Table 5 - Example binarization table for LFNST index

[0147] lfnst_idx Bin 0 00 1 01 2 10 3 11

[0148] In an example, three bits may be used to determine and / or signal an MTS index, one of which may be used to indicate whether MTS (or DCT-II) is applied, and the other two bits may be used to code the MTS index (e.g., indexes 1 to 4), for example, as illustrated in Table 6 below.

[0149] Table 6 - Example binarization table for MTS index

[0150] mts_idx Bin 0 0 1 100 2 101 3 110 4 111

[0151] In an example, the number of MTS transform candidates (eg, the maximum number of MTS transform indexes) may be set to 2, 4, or 6, and a truncated binary code may be used to represent the MTS index, for example, as illustrated in Table 7 below.

[0152] Table 7 - Example binarization table for MTS index

[0153]

[0154] Using coefficient sign prediction, the reconstructed residual value can be determined based on negative and positive sign hypotheses associated with the transform coefficients, and the hypothesis that minimizes the cost (e.g., determined based on a cost function as will be shown herein) can be selected. Figure 7 An example of coefficient sign prediction is illustrated, where costs associated with multiple sign hypotheses can be determined by measuring discontinuities across block boundaries that may be caused by the hypotheses, and the hypothesized symbol associated with the minimum cost can be selected as the predicted coefficient symbol. In an example, the cost (e.g., a corresponding cost function) can be defined as the sum of absolute second-order derivatives in the residual domain for the previous row and / or left column of the current video block, as illustrated below:

[0155]

[0156] where R can represent the reconstructed neighbors (e.g., from the previous row and / or left column), P can represent the prediction for the current block, and r can represent the residual that can be generated from the hypothesis. (-R -1 The value of +2R0-P1) may be calculated once per block (eg, only once) and the residual may be subtracted from the calculated value. The coefficient sign prediction techniques described herein may be applied to MTS (eg, including one or more DCT-based transforms) and / or LFNST.

[0157] The index of the transform to be used for a video block (e.g., a coding unit, a coding block, etc.) may be predicted, for example, by testing a plurality (e.g., some or all) of hypotheses (e.g., candidate transforms) and selecting the hypothesis that minimizes the cost (e.g., the difference or distance between a sample value in a current block and a neighboring sample value of one or more rows / columns). For example, assuming that N transform pairs (also referred to herein as N transforms) are available for testing at the encoder side, and each transform pair may be identified (e.g., indexed) with a transform index TrIdx (e.g., TdIdx=0:N-1), the encoder may test the N transform pairs on the dequantized coefficients (e.g., by performing an inverse transform on the dequantized coefficients using the N transform pairs) to generate N residual blocks corresponding to the N transform pairs. The encoder may compare the residual with residuals associated with one or more rows or columns of neighboring samples (e.g., in a similar manner as described herein for transform sign prediction) to determine a hypothesis cost associated with each transform pair, e.g., based on the sum of absolute second order derivatives in the residual domain for the previous row and / or left column of the current video block, as exemplified below:

[0158]

[0159] Where R can represent the reconstructed neighbor, P can represent the prediction for the current block, and r can represent the residual that can be associated with the current hypothesis (eg, the current hypothesis transform). x,1 can represent the top row of prediction samples for the current block, and P 1，y It is possible to represent the left column prediction samples for the current block. Therefore, the hypothesis cost can be determined based on the reconstructed neighboring samples, the prediction samples for the current block (e.g., a subset of the prediction samples for the current block, such as the prediction samples adjacent to the neighboring samples of a row or column), and the residual value for the current block that can be associated with the current hypothesis transform. The encoder can then predict the transform (e.g., transform pair) to be used for the current block based on the corresponding hypothesis costs calculated for the N transforms or transform pairs (e.g., by selecting the transform pair with the lowest cost). An example of transform index prediction (e.g., to be performed by an encoder and / or decoder) can be illustrated by the following Table 8.

[0160] Table 8 - Example Transform Index Prediction

[0161]

[0162] In an example, the transform set (e.g., transform pair) available for a video block may depend on the size of the video block (e.g., TrSize shown in Table 8) and / or the intra-prediction mode used for the video block (e.g., indicated by IntraPredMode shown in Table 8). In an example, the available transforms (e.g., transform pairs) may be defined independently (e.g., independent of the block size and / or intra-prediction mode). In either case, a corresponding hypothetical cost associated with applying the available transforms (e.g., transform pairs) to the video block may be determined, and a transform (e.g., transform pair) may be selected from the available transform pairs based on the hypothetical cost (e.g., the selected transform or transform pair may be the transform or transform pair with the lowest cost). The transform prediction techniques described herein may be applied by an encoder and / or a decoder (e.g., to obtain the same prediction on both sides), and these techniques may improve coding gain because, for example, the difference between the predicted index and the actual transform index to be used may be sent (e.g., instead of the actual transform index). For example, if the transform index predicted by the encoder for a video block is 2 and the actual transform index used for the video block is 4, then the difference between the two indices (e.g., -2) may be signaled (e.g., instead of the actual index 4). As prediction accuracy increases, even less information may be sent. For example, if the encoder and decoder can consistently and accurately predict the transform that may be applied to the video block, then the signaling of the transform index or difference described above may be skipped or bypassed, and the encoder and decoder may apply the predicted transform to the video block.

[0163] A set of candidate transforms may be sorted by an encoder and / or decoder, for example, based on respective hypothesis costs associated with the candidate transforms.The transform index may then be determined based on the sorted (eg, re-ordered) transform list. Figure 8 Example operations that may be associated with transform ordering are illustrated. As shown, variables representing a minimum hypothesized cost (e.g., bestCost), an index of a transform with the minimum hypothesized cost (e.g., bestIdx), and a current transform index (TrIdx) may be initialized at 802. Next, starting at 804, for each TrIdx that is less than a maximum transform coefficient (N), a transform representing TrIdx may be (e.g., hypothetically) applied to a reconstruction of a video block at 806, and a hypothesized cost associated with the application of the transform may be determined as 808 (e.g., using a cost function as shown in Table 9). The hypothesized costs may then be used to update the minimum hypothesized cost (e.g., bestCost) and the transform coefficient associated with the minimum hypothesized cost (e.g., bestIdx), as shown at 810. Through these iterative operations, N transforms may be ordered (e.g., reordered) into a transform list based on the respective hypothesized costs associated with applying the transforms to the video block. The index of the transform on the transform list may then be used (eg, by an encoder and / or decoder) to convey or determine which transform from the transform list is applicable to the video block.

[0164] Table 9 below illustrates an example of transform index ordering or reordering (eg, based on assumed costs associated with the N candidate transforms).

[0165] Table 9 - Example Transform Index Ordering

[0166]

[0167] As shown in Table 9, a cost function (e.g., cost(TrIdx)) may be used to determine a hypothetical cost associated with applying a candidate transform represented by TrIdx to a current video block, e.g., based on the sum of absolute second-order derivatives in the residual domain of the previous row and / or left column of the current video block, where R in the cost function can represent a reconstructed neighbor for the current video block, P in the cost function can represent a prediction for the current block, and r can represent a residual that may be associated with a candidate transform (e.g., a current hypothetical transform). For example, P x,1 can represent the top row of prediction samples for the current block, and P 1，y Thus, a hypothesized cost associated with a candidate transform may be determined based on reconstructed neighboring samples, prediction samples for the current block (e.g., a subset of the prediction samples for the current block, such as prediction samples adjacent to a row or column of neighboring samples), and a residual value for the current video block that may be associated with the candidate transform.

[0168] In the examples shown above, transform indices associated with N candidate transforms (e.g., which may be stored in a TrList) may be sorted according to respective costs associated with applying the transforms to the current video block, and the sorted indices may be stored by the encoder and / or decoder (e.g., in a ReorderedTrList). The current transform index (e.g., curTrIdx) representing the transform to be used may then be mapped to the reordered transform index (e.g., ReorderedTrIdx). It should be noted that in some embodiments, transform index sorting or reordering techniques may be employed if (e.g., only if) N or more coefficients (e.g., N can represent the number of candidate transforms) are available in the current video block, or if N or more coefficients in the current video block have an absolute value greater than a predefined threshold. In these embodiments, parameters associated with the transform (e.g., with the MTS and / or LFNST transform) may be coded after the coefficients associated with the transform have been coded.

[0169] The transform index prediction and / or ordering techniques described herein may be applicable to MTS-based transforms. In some examples, a fixed number (e.g., four) of MTS transform pairs may be defined or available for (e.g., each) coding unit, while in other examples, the number of available MTS transform pairs may vary (e.g., 2, 4, or 6 transform pairs) based on one or more thresholds (e.g., which may be signaled at the SPS level). Depending on the number of defined or available transform pairs (e.g., 2, 4, or 6), transform index prediction may be invoked to obtain a transform index that can represent the transform to be applied. Signaling associated with the MTS may be altered to take advantage of the prediction. For example, an index prediction indication (e.g., cu_predicted_mts_idx_flag) may be signaled before the MTS index (e.g., in the video bitstream). If the predicted MTS index (e.g., predicted based on cost and / or represented by predMtsIdx) is equal to the current MTS index (e.g., determined based on rate distortion and represented by MtsIdx), the indication may be set to one (or true), in which case the signaling of the current MTS index may be skipped (e.g., not signaled by the encoder or retrieved from the bitstream by the decoder) and the predicted MTS index value may be used (e.g., predicted by the decoder). In an example, if the predicted MTS index is not equal to the current MTS index or if transform prediction is not performed (e.g., performed by the encoder), the related indication (e.g., cu_predicted_mts_idx_flag) may be set to zero (or false), in which case the actual MTS index to be applied may be signaled to the decoder. In an example, if the predicted MTS index is not equal to the current MTS index, the related indication (e.g., cu_predicted_mts_idx_flag) may be set to one (or true), and the difference between the predicted MTS index and the current MTS index may be signaled. In this case, the decoder may perform prediction (e.g., similar to the encoder) to determine the predicted MTS index, and use the predicted MTS index and the signaled difference to determine the actual MTS index to be used. In some examples, if two (e.g., only two) MTS candidates are available, the above method may not be used, because in this case, the MTS information may have been conveyed with one bit.

[0170] In an example, when cu_predicted_mts_idx_flag described herein is set to zero or false, MTS index prediction based on the techniques described herein may be performed and the predicted transform index may be removed from the list of signaled indices. In an example, if cu_predicted_mts_idx_flag is set to zero or false, the index of a non-MTS transform (e.g., DCT-II) may be predicted using the techniques described herein, and the index of the non-MTS transform (e.g., DCT-II) may be coded / signaled as an MTS transform (e.g., using MTS index 0). In these examples, an MTS indication (e.g., for distinguishing an MTS transform from a non-MTS transform) may not be signaled.

[0171] In an example, the number of primary (or secondary) transforms tested (e.g., based on cost) may be greater than the number of transform indices signaled, e.g., because there may be no signaling overhead when using cu_predicted_mts_idx_flag. For example, testing (e.g., prediction) may be performed for (e.g., always for) six transform pairs, and the number of indices actually signaled may depend on a threshold that may be signaled in the SPS. In an example, the number of primary (or secondary) transforms tested may be less than the number of indices signaled, e.g., because such testing may increase the complexity of the decoder. For example, testing (e.g., prediction) may be performed for (e.g., always for) two transform pairs, and the number of indices actually signaled may depend on a threshold that may be signaled in the SPS.

[0172] In an example, an encoder may determine a suitable transform for a video block. The encoder may order (e.g., reorder) transform indices (e.g., MTS indices) based on respective assumed costs associated with applying the transforms to the video block to derive a reordered transform list. The encoder may signal a transform index (e.g., a reordered transform index) that may indicate a position of a suitable transform on the reordered transform list to a decoder. The decoder may perform a similar reordering operation (e.g., based on assumed costs associated with applying a plurality of candidate transforms to the video block) and may derive a reordered transform list that is the same as the reordered transform list derived by the encoder. The decoder may then determine a current transform index (e.g., a current MTS index) based on the reordered transform list and the signaled transform index (e.g., the reordered transform index) (e.g., by mapping the current transform index to a signaled index associated with the reordered transform list).

[0173] Truncated Rice binarization may be used to code the reordered indices to reduce signaling cost. In an example, a Rice parameter applicable to code the reordered transform indices may be adjusted based on the number of transform pairs being evaluated (e.g., 2, 4, or 6). For example, if there are two transform pairs to be evaluated and / or reordered, the Rice parameter may have a smaller value (e.g., 1 or 2), and if there are six transform pairs to be evaluated and / or reordered, the Rice parameter may have a larger value (e.g., greater than 2).

[0174] The transform index prediction and / or ordering (e.g., reordering) techniques described herein may be applied to a transform that includes an MTS transform and a DCT-II transform. For example, when applying the transform prediction and / or reordering techniques described herein, the DCT-II transform may be included as a candidate to be evaluated (e.g., together with the MTS transform). This may further reduce signaling costs, for example, because a single indication (e.g., cu_predicted_mts_idx_flag) may be used to indicate whether the transform index should be predicted for both the DCT-II transform and the MTS transform (e.g., no additional flag may be needed to indicate whether DCT-II or MTS is used).

[0175] The transform index prediction and / or ordering (e.g., reordering) techniques described herein may be applied to secondary transforms including LFNST transforms. For example, an encoder may test multiple (e.g., all) candidate LFNST transforms by measuring the cost (e.g., discontinuity) associated with adjacent samples of one or more rows or columns of a current video block to predict a suitable transform (e.g., a transform with the lowest cost) among the candidates and / or reorder the candidate transforms. In the case of transform prediction, an indication (e.g., cu_predicted_lfnst_idx_flag) may be signaled to indicate whether the decoder should predict the transform index (e.g., no such index is signaled). In the case of transform reordering, a reordered index indicating the position of the suitable transform on the reordered transform list may be signaled, and the decoder may derive the suitable transform based on the signaled index and by determining the reordered transform list using the same (e.g., similar) technique applied by the encoder.

[0176] In an example, the techniques described herein for transform index prediction and / or reordering may not be used directly with transform symbol prediction. One reason for this may be that transform symbol prediction may utilize knowledge about transform indices (e.g., in order to perform an inverse transform with multiple hypotheses about the sign), and therefore, if the transform index is to be derived, then symbol prediction may not be performed. One or more of the following methods may be used to resolve (e.g., handle) conflicts between transform symbol prediction and transform index prediction.

[0177] In one example, at least one of transform symbol prediction or transform index prediction may not be allowed or disabled. An indicator (e.g., a flag) may be signaled to indicate whether transform symbol prediction or transform index prediction is used. The indication may also be derived. For example, if cu_predicted_mts_idx_flag and / or cu_predicted_lfnst_index_flag described herein are signaled in the video bitstream, then a determination may be made that transform index prediction is enabled (e.g., used) and transform symbol prediction is disabled (e.g., not used).

[0178] In one example, a combined assumption about the transform symbol and the transform index may be made. The assumption about the transform symbol may be augmented with an assumption about the transform index (e.g., MTS index and / or LFNST index). For example, for N transform symbols, there may be 2 possible transform symbols. N possible hypotheses. If M transformation pairs are available for testing, then there may be M*2 N At the encoder side and / or the decoder side, multiple (eg, all) possible transform indices may be used to convert 2 N The hypothesis is repeated M times, and the hypothesis that minimizes the cost may be selected for determining (e.g., predicting) the transform sign and / or the transform index. In an example, a combined hypothesis about the transform sign and the transform index may be made when (e.g., only when) the number of transform pairs M is less than a predefined threshold and when the test hypothesis can be within an acceptable complexity range. For example, the combined hypothesis may be tested when (e.g., only when) two transform pairs are involved.

[0179] Although the examples provided herein may assume that media content is streamed to a display device, there is no particular restriction on the type of display device that may benefit from the example techniques described herein. For example, a display device may be a television, a projector, a mobile phone, a tablet computer, etc. In addition, the example techniques described herein may be applicable not only to streaming use cases, but also to teleconference settings. In addition, decoders and displays as described herein may be separate devices or may be parts of the same device. For example, a set-top box may decode an incoming video stream and (for example, subsequently) provide the decoded stream to a display device (for example, via HDMI), and information about viewing conditions such as viewing distance may be sent from the display device to the set-top box (for example, via HDMI).

[0180] Although features and elements are described above in specific combinations, it will be understood by those of ordinary skill in the art that each feature or element may be used alone or in any combination with other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (sent via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as built-in hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and digital versatile disks (DVDs)). A processor associated with software may be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. A video decoding device, the video decoding device comprising: A processor, the processor being configured to: obtaining a transform index value associated with a video block, wherein the transform index value indicates a position on an ordered transform list of a transform to be used for the video block; determining respective hypothesized costs associated with applying a plurality of transforms to the video block; sorting the plurality of transformations according to the determined assumed costs, wherein the sorted transformation list is obtained according to a result of the sorting; selecting the transform to be used for the video block based on the ordered transform list and the transform index value; as well as The video block is decoded based at least on the selected transform.

2. The video decoding device of claim 1, wherein the plurality of transforms comprises two or more multiple transform selection (MTS) transforms.

3. A video decoding device according to claim 1 or claim 2, wherein the multiple transforms include discrete cosine transforms. 4 . The video decoding apparatus of claim 1 , wherein the plurality of transforms comprises two or more low frequency non-separable transforms (LFNSTs).

5. The video decoding apparatus of any one of claims 1 to 4, wherein the respective hypothesized costs associated with applying the plurality of transforms to the video block are determined based on samples of the video block and one or more rows or columns adjacent to the video block. 6 . The video decoding device according to claim 1 , wherein the processor is configured to obtain the transform index value comprises the processor being configured to determine the transform index based on a code included in the video data.

7. The video decoding device of claim 6, wherein the value of the code depends on the number of transforms on the ordered transform list.

8. A method for video decoding, the method comprising: obtaining a transform index value associated with a video block, wherein the transform index value indicates a position on an ordered transform list of a transform to be used for the video block; determining respective hypothesized costs associated with applying a plurality of transforms to the video block; sorting the plurality of transformations according to the determined assumed costs, wherein the sorted transformation list is obtained according to a result of the sorting; selecting the transform to be used for the video block based on the ordered transform list and the transform index value; as well as The video block is decoded based at least on the selected transform.

9. The method of claim 8, wherein the plurality of transforms comprises two or more Multiple Transform Selection (MTS) transforms.

10. A method according to claim 8 or claim 9, wherein the plurality of transforms comprises discrete cosine transforms.

11. The method of claim 8, wherein the plurality of transforms comprises two or more low frequency non-separable transforms (LFNSTs).

12. The method of any one of claims 8 to 11, wherein the respective hypothesized costs associated with applying the plurality of transforms to the video block are determined based on samples of the video block and one or more rows or columns neighboring the video block.

13. The method according to any one of claims 8 to 12, wherein obtaining the transform index value comprises determining the transform index value based on a code included in video data. The method of claim 13 , wherein the value of the code depends on the number of transforms on the ordered transform list.

15. A video encoding device, the video encoding device comprising: A processor, the processor being configured to: determining respective hypothesized costs associated with applying a plurality of transforms to the video block; sorting the plurality of transformations according to the determined assumed costs, wherein a sorted transformation list is obtained according to a result of the sorting; selecting a transform for the video block; determining a transform index value associated with the selected transform, wherein the transform index value indicates a position of the selected transform on the sorted transform list; encoding the video block in the video data based at least on the selected transform; as well as An indication of the transform index value in the video data is encoded.

16. The video encoding apparatus of claim 15, wherein the plurality of transforms comprises two or more Multiple Transform Select (MTS) transforms.

17. A video encoding apparatus according to claim 15 or claim 16, wherein the plurality of transforms comprises discrete cosine transforms.

18. The video encoding apparatus of claim 15, wherein the plurality of transforms comprises two or more low frequency non-separable transforms (LFNSTs).

19. The video encoding apparatus of any one of claims 15 to 18, wherein the respective hypothesized costs associated with applying the plurality of transforms to the video block are determined based on samples of the video block and one or more rows or columns neighboring the video block.

20. The video encoding device of any one of claims 15 to 19, wherein the processor being configured to encode the indication of the transform index value comprises the processor being configured to determine a code for the transform index value based on binarization of the transform index.

21. The video encoding device of claim 20, wherein the code is determined based at least on the number of transforms on the ordered transform list.

22. A method for video encoding, the method comprising: determining respective hypothesized costs associated with applying a plurality of transforms to the video block; sorting the plurality of transformations according to the determined assumed costs, wherein a sorted transformation list is obtained according to a result of the sorting; selecting a transform for the video block; determining a transform index value associated with the selected transform, wherein the transform index value indicates a position of the selected transform on the sorted transform list; encoding the video block in the video data based at least on the selected transform; as well as An indication of the transform index value in the video data is encoded.

23. The method of claim 22, wherein the plurality of transforms comprises two or more Multiple Transform Selection (MTS) transforms.

24. A method according to claim 22 or claim 23, wherein the plurality of transforms comprises discrete cosine transforms.

25. The method of claim 22, wherein the plurality of transforms comprises two or more low frequency non-separable transforms (LFNSTs).

26. The method of any one of claims 22 to 25, wherein the respective hypothesized costs associated with applying the plurality of transforms to the video block are determined based on samples of the video block and one or more rows or columns neighboring the video block.

27. The method of any one of claims 22 to 26, wherein encoding the transform index value comprises determining a code for the transform index value based on binarization of the transform index value.

28. The method of claim 27, wherein the code is determined based at least on the number of transforms on the ordered transform list.

29. A computer program product stored on a non-transitory computer readable medium and comprising program code instructions for implementing the steps of the method according to at least one of claims 8 to 14 or claims 22 to 28 when executed by a processor.

30. A computer program comprising program code instructions for implementing the steps of the method according to at least one of claims 8 to 14 or claims 22 to 28 when executed by a processor.

31. Video data comprising information representing the video block and the transform index value encoded based on the method according to any one of claims 22 to 28.

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